Programs & Examples On #Instaweb

How to create a bash script to check the SSH connection?

Below ssh command should have an exit code of 0 on a successful connection and a non-zero value otherwise.

ssh -q -o BatchMode=yes [email protected] exit

if [ $? != "0" ]; then
    echo "Connection failed"

Change package name for Android in React Native

If you are using VSCode and Windows.

1.Press Control + Shift + F.

2.Find Your Package Name and Replace All with your new Package Name.

  1. type "cd android"

  2. type "./gradlew clean"

How do I diff the same file between two different commits on the same branch?

If you want to make a diff with more than one file, with the method specified by @mipadi:

E.g. diff between HEAD and your master, to find all .coffee files:

git diff master..HEAD -- `find your_search_folder/ -name '*.coffee'`

This will recursively search your your_search_folder/ for all .coffee files and make a diff between them and their master versions.

What are the differences between Deferred, Promise and Future in JavaScript?

A Promise represents a proxy for a value not necessarily known when the promise is created. It allows you to associate handlers to an asynchronous action's eventual success value or failure reason. This lets asynchronous methods return values like synchronous methods: instead of the final value, the asynchronous method returns a promise of having a value at some point in the future.

The deferred.promise() method allows an asynchronous function to prevent other code from interfering with the progress or status of its internal request. The Promise exposes only the Deferred methods needed to attach additional handlers or determine the state (then, done, fail, always, pipe, progress, state and promise), but not ones that change the state (resolve, reject, notify, resolveWith, rejectWith, and notifyWith).

If target is provided, deferred.promise() will attach the methods onto it and then return this object rather than create a new one. This can be useful to attach the Promise behavior to an object that already exists.

If you are creating a Deferred, keep a reference to the Deferred so that it can be resolved or rejected at some point. Return only the Promise object via deferred.promise() so other code can register callbacks or inspect the current state.

Simply we can say that a Promise represents a value that is not yet known where as a Deferred represents work that is not yet finished.

enter image description here

Cause of a process being a deadlock victim

The answers here are worth a try, but you should also review your code. Specifically have a read of Polyfun's answer here: How to get rid of deadlock in a SQL Server 2005 and C# application?

It explains the concurrency issue, and how the usage of "with (updlock)" in your queries might correct your deadlock situation - depending really on exactly what your code is doing. If your code does follow this pattern, this is likely a better fix to make, before resorting to dirty reads, etc.

How can I make window.showmodaldialog work in chrome 37?

I wouldn't try to temporarily enable a deprecated feature. According to the MDN documentation for showModalDialog, there's already a polyfill available on Github.

I just used that to add windows.showModalDialog to a legacy enterprise application as a userscript, but you can obviously also add it in the head of the HTML if you have access to the source.

Origin http://localhost is not allowed by Access-Control-Allow-Origin

You've got two ways to go forward:


If this API supports JSONP, the easiest way to fix this issue is to add &callback to the end of the URL. You can also try &callback=. If that doesn't work, it means the API does not support JSONP, so you must try the other solution.

Proxy Script

You can create a proxy script on the same domain as your website in order to avoid the cross-origin issues. This will only work with HTTP URLs, not HTTPS URLs, but it shouldn't be too difficult to modify if you need that.

// File Name: proxy.php
if (!isset($_GET['url'])) {
    die(); // Don't do anything if we don't have a URL to work with
$url = urldecode($_GET['url']);
$url = 'http://' . str_replace('http://', '', $url); // Avoid accessing the file system
echo file_get_contents($url); // You should probably use cURL. The concept is the same though

Then you just call this script with jQuery. Be sure to urlencode the URL.

    url      : 'proxy.php?',
    type     : 'GET',
    dataType : 'json'
}).done(function(data) {
    console.log(data.results.result[1].category); // Do whatever you want here

The Why

You're getting this error because of XMLHttpRequest same origin policy, which basically boils down to a restriction of ajax requests to URLs with a different port, domain or protocol. This restriction is in place to prevent cross-site scripting (XSS) attacks.

More Information

Our solutions by pass these problems in different ways.

JSONP uses the ability to point script tags at JSON (wrapped in a javascript function) in order to receive the JSON. The JSONP page is interpreted as javascript, and executed. The JSON is passed to your specified function.

The proxy script works by tricking the browser, as you're actually requesting a page on the same origin as your page. The actual cross-origin requests happen server-side.

PHP json_encode encoding numbers as strings

Note that since PHP 5.3.3, there's a flag for auto-converting numbers (the options parameter was added in PHP 5.3.0):

$arr = array( 'row_id' => '1', 'name' => 'George' );
echo json_encode( $arr, JSON_NUMERIC_CHECK ); // {"row_id":1,"name":"George"}

Git keeps asking me for my ssh key passphrase

If you've tried ssh-add and you're still prompted to enter your passphrase then try using ssh-add -K. This adds your passphrase to your keychain.

Update: if you're using macOS Sierra then you likely need to do another step as the above might no longer work. Add the following to your ~/.ssh/config:

Host *
  UseKeychain yes

Find directory name with wildcard or similar to "like"

find supports wildcard matches, just add a *:

find / -type d -name "ora10*"

Why do I get a warning icon when I add a reference to an MEF plugin project?

Make sure you have the projects targeting the same framework version. Most of the times the reason would be that current project ( where you are adding reference of another project ) points to a different .net framework version than the rest ones.

Plot bar graph from Pandas DataFrame

To plot just a selection of your columns you can select the columns of interest by passing a list to the subscript operator:

ax = df[['V1','V2']].plot(kind='bar', title ="V comp", figsize=(15, 10), legend=True, fontsize=12)

What you tried was df['V1','V2'] this will raise a KeyError as correctly no column exists with that label, although it looks funny at first you have to consider that your are passing a list hence the double square brackets [[]].

import matplotlib.pyplot as plt
ax = df[['V1','V2']].plot(kind='bar', title ="V comp", figsize=(15, 10), legend=True, fontsize=12)
ax.set_xlabel("Hour", fontsize=12)
ax.set_ylabel("V", fontsize=12)

enter image description here

Activate tabpage of TabControl

tabControl1.SelectedTab = MyTab;

What is the difference between display: inline and display: inline-block?

All answers above contribute important info on the original question. However, there is a generalization that seems wrong.

It is possible to set width and height to at least one inline element (that I can think of) – the <img> element.

Both accepted answers here and on this duplicate state that this is not possible but this doesn’t seem like a valid general rule.


img {_x000D_
  width: 200px;_x000D_
  height: 200px;_x000D_
  border: 1px solid red;_x000D_
<img src="#" />

The img has display: inline, but its width and height were successfully set.

Count the number of occurrences of a string in a VARCHAR field?

Here is a function that will do that.

CREATE FUNCTION count_str(haystack TEXT, needle VARCHAR(32))
    RETURN ROUND((CHAR_LENGTH(haystack) - CHAR_LENGTH(REPLACE(haystack, needle, ""))) / CHAR_LENGTH(needle));

Setting up a websocket on Apache?

I can't answer all questions, but I will do my best.

As you already know, WS is only a persistent full-duplex TCP connection with framed messages where the initial handshaking is HTTP-like. You need some server that's listening for incoming WS requests and that binds a handler to them.

Now it might be possible with Apache HTTP Server, and I've seen some examples, but there's no official support and it gets complicated. What would Apache do? Where would be your handler? There's a module that forwards incoming WS requests to an external shared library, but this is not necessary with the other great tools to work with WS.

WS server trends now include: Autobahn (Python) and Socket.IO (Node.js = JavaScript on the server). The latter also supports other hackish "persistent" connections like long polling and all the COMET stuff. There are other little known WS server frameworks like Ratchet (PHP, if you're only familiar with that).

In any case, you will need to listen on a port, and of course that port cannot be the same as the Apache HTTP Server already running on your machine (default = 80). You could use something like 8080, but even if this particular one is a popular choice, some firewalls might still block it since it's not supposed to be Web traffic. This is why many people choose 443, which is the HTTP Secure port that, for obvious reasons, firewalls do not block. If you're not using SSL, you can use 80 for HTTP and 443 for WS. The WS server doesn't need to be secure; we're just using the port.

Edit: According to Iharob Al Asimi, the previous paragraph is wrong. I have no time to investigate this, so please see his work for more details.

About the protocol, as Wikipedia shows, it looks like this:

Client sends:

GET /mychat HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==
Sec-WebSocket-Protocol: chat
Sec-WebSocket-Version: 13

Server replies:

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk=
Sec-WebSocket-Protocol: chat

and keeps the connection alive. If you can implement this handshaking and the basic message framing (encapsulating each message with a small header describing it), then you can use any client-side language you want. JavaScript is only used in Web browsers because it's built-in.

As you can see, the default "request method" is an initial HTTP GET, although this is not really HTTP and looses everything in common with HTTP after this handshaking. I guess servers that do not support

Upgrade: websocket
Connection: Upgrade

will reply with an error or with a page content.

jQuery: how to find first visible input/select/textarea excluding buttons?

You may try below code...

<script src=""></script>_x000D_
<input type="text" />_x000D_
<input type="text" />_x000D_
<input type="text" />_x000D_
<input type="text" />_x000D_
<input type="text" />_x000D_
<input type="submit" />_x000D_

How do I fix the indentation of an entire file in Vi?

The master of all commands is


This indents the entire file!

And below are some of the simple and elegant commands used to indent lines quickly in Vim or gVim.

To indent the all the lines below the current line


To indent the current line


To indent n lines below the current line


For example, to indent 4 lines below the current line


To indent a block of code, go to one of the braces and use command


How to programmatically modify WCF app.config endpoint address setting?

Is this on the client side of things??

If so, you need to create an instance of WsHttpBinding, and an EndpointAddress, and then pass those two to the proxy client constructor that takes these two as parameters.

// using System.ServiceModel;
WSHttpBinding binding = new WSHttpBinding();
EndpointAddress endpoint = new EndpointAddress(new Uri("http://localhost:9000/MyService"));

MyServiceClient client = new MyServiceClient(binding, endpoint);

If it's on the server side of things, you'll need to programmatically create your own instance of ServiceHost, and add the appropriate service endpoints to it.

ServiceHost svcHost = new ServiceHost(typeof(MyService), null);

                           new WSHttpBinding(), 

Of course you can have multiple of those service endpoints added to your service host. Once you're done, you need to open the service host by calling the .Open() method.

If you want to be able to dynamically - at runtime - pick which configuration to use, you could define multiple configurations, each with a unique name, and then call the appropriate constructor (for your service host, or your proxy client) with the configuration name you wish to use.

E.g. you could easily have:

<endpoint address="http://mydomain/MyService.svc"
        binding="wsHttpBinding" bindingConfiguration="WSHttpBinding_IASRService"
            <dns value="localhost" />

<endpoint address="https://mydomain/MyService2.svc"
        binding="wsHttpBinding" bindingConfiguration="SecureHttpBinding_IASRService"
            <dns value="localhost" />

<endpoint address="net.tcp://mydomain/MyService3.svc"
        binding="netTcpBinding" bindingConfiguration="NetTcpBinding_IASRService"
            <dns value="localhost" />

(three different names, different parameters by specifying different bindingConfigurations) and then just pick the right one to instantiate your server (or client proxy).

But in both cases - server and client - you have to pick before actually creating the service host or the proxy client. Once created, these are immutable - you cannot tweak them once they're up and running.


Find everything between two XML tags with RegEx

In our case, we receive an XML as a String and need to get rid of the values that have some "special" characters, like &<> etc. Basically someone can provide an XML to us in this form:

     <to>jenice & carl </to>
     <from>your neighbor <; </from>

So I need to find in that String the values jenice & carl and your neighbor <; and properly escape & and < (otherwise this is an invalid xml if you later pass it to an engine that shall rename unnamed).

Doing this with regex is a rather dumb idea to begin with, but it's cheap and easy. So the brave ones that would like to do the same thing I did, here you go:

    String xml = ...
    Pattern p = Pattern.compile("<(.+)>(?!\\R<)(.+)</(\\1)>");
    Matcher m = p.matcher(xml);
    String result = m.replaceAll(mr -> {
        if ("&")) {
            return "<" + + ">" + + "+ some change" + "</" + + ">";
        return "<" + + ">" + + "</" + + ">";

TCPDF ERROR: Some data has already been output, can't send PDF file

For those who are still facing this issue try adding:


before the loadHtml call and add


after the call.

This solved it for me.

Make Div overlay ENTIRE page (not just viewport)?

body:before {
    content: " ";
    width: 100%;
    height: 100%;
    position: fixed;
    z-index: -1;
    top: 0;
    left: 0;
    background: rgba(0, 0, 0, 0.5);

How to integrate sourcetree for gitlab

It worked for me, but only with https link in repository setting (Repository => Repository Settings). You need to change setting to:

URL / path: https://**********.com/username/project.git
Host Type - Stash
Host Root URL - your root URL to GitLab (example:https://**********.com/) 
Username - leave blank

or in some cases if you have ssh url like:

[email protected]:USER/REPOSITORY.git

and your email like:

[email protected]

then this settings should be work:

URL / path: https://test%[email protected]:USER/REPOSITORY.git

"Could not find the main class" error when running jar exported by Eclipse

Right click on the project. Go to properties. Click on Run/Debug Settings. Now delete the run config of your main class that you are trying to run. Now, when you hit run again, things would work just fine.

Reference - What does this regex mean?

The Stack Overflow Regular Expressions FAQ

See also a lot of general hints and useful links at the tag details page.

Online tutorials


Character Classes

Escape Sequences


(Also see "Flavor-Specific Information ? Java ? The functions in Matcher")





Common Tasks

Advanced Regex-Fu

Flavor-Specific Information

(Except for those marked with *, this section contains non-Stack Overflow links.)

General information

(Links marked with * are non-Stack Overflow links.)

Examples of regex that can cause regex engine to fail

Tools: Testers and Explainers

(This section contains non-Stack Overflow links.)

c# dictionary one key many values

Microsoft just added an official prelease version of exactly what you're looking for (called a MultiDictionary) available through NuGet here:

Info on usage and more details can be found through the official MSDN blog post here:

I'm the developer for this package, so let me know either here or on MSDN if you have any questions about performance or anything.

Hope that helps.


The MultiValueDictionary is now on the corefxlab repo, and you can get the NuGet package from this MyGet feed.

NPM doesn't install module dependencies

I had very similar issue, removing entire node_modules folder and re-installing worked for me. Learned this trick from the IT Crowd show!

rm -rf node_modules
npm install

Read/Write String from/to a File in Android

I'm a bit of a beginner and struggled getting this to work today.

Below is the class that I ended up with. It works but I was wondering how imperfect my solution is. Anyway, I was hoping some of you more experienced folk might be willing to have a look at my IO class and give me some tips. Cheers!

public class HighScore {
    File data = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator);
    File file = new File(data, "highscore.txt");
    private int highScore = 0;

    public int readHighScore() {
        try {
            BufferedReader br = new BufferedReader(new FileReader(file));
            try {
                highScore = Integer.parseInt(br.readLine());
            } catch (NumberFormatException | IOException e) {
        } catch (FileNotFoundException e) {
            try {
            } catch (IOException ioe) {
        return highScore;

    public void writeHighScore(int highestScore) {
        try {
            BufferedWriter bw = new BufferedWriter(new FileWriter(file));
        } catch (IOException e) {

Assertion failure in dequeueReusableCellWithIdentifier:forIndexPath:

In my case, the crash happened when I calleddeselectRowAtIndexPath:

The line was [tableView deselectRowAtIndexPath:indexPath animated:YES];

Changing it to [self.tableView deselectRowAtIndexPath:indexPath animated:YES]; FIXED MY PROBLEM!

Hope this helps anyone

How to detect online/offline event cross-browser?

The window.navigator.onLine attribute and its associated events are currently unreliable on certain web browsers (especially Firefox desktop) as @Junto said, so I wrote a little function (using jQuery) that periodically checks the network connectivity status and raise the appropriate offline and online events:

// Global variable somewhere in your app to replicate the 
// window.navigator.onLine variable (this last is not modifiable). It prevents
// the offline and online events to be triggered if the network
// connectivity is not changed
var IS_ONLINE = true;

function checkNetwork() {
    // Empty file in the root of your public vhost
    url: '/networkcheck.txt',
    // We don't need to fetch the content (I think this can lower
    // the server's resources needed to send the HTTP response a bit)
    type: 'HEAD',
    cache: false, // Needed for HEAD HTTP requests
    timeout: 2000, // 2 seconds
    success: function() {
      if (!IS_ONLINE) { // If we were offline
        IS_ONLINE = true; // We are now online
        $(window).trigger('online'); // Raise the online event
    error: function(jqXHR) {
      if (jqXHR.status == 0 && IS_ONLINE) {
        // We were online and there is no more network connection
        IS_ONLINE = false; // We are now offline
        $(window).trigger('offline'); // Raise the offline event
      } else if (jqXHR.status != 0 && !IS_ONLINE) {
        // All other errors (404, 500, etc) means that the server responded,
        // which means that there are network connectivity
        IS_ONLINE = true; // We are now online
        $(window).trigger('online'); // Raise the online event

You can use it like this:

// Hack to use the checkNetwork() function only on Firefox 
// (
// (But it may be too restrictive regarding other browser
// who does not properly support online / offline events)
if (!(window.mozInnerScreenX == null)) {
    window.setInterval(checkNetwork, 30000); // Check the network every 30 seconds

To listen to the offline and online events (with the help of jQuery):

$(window).bind('online offline', function(e) {
  if (!IS_ONLINE || !window.navigator.onLine) {
    alert('We have a situation here');
  } else {
    alert('Battlestation connected');

bootstrap datepicker change date event doesnt fire up when manually editing dates or clearing date

Try with below code is working for me

var date_input_field = $('input[name="date"]');
    date_input_field .datepicker({
        dateFormat: '/dd/mm/yyyy',
        container: container,
        todayHighlight: true,
        autoclose: true,
    }).on('change', function(selected){

Regex for allowing alphanumeric,-,_ and space

var string = 'test- _ 0Test';
string.match(/^[-_ a-zA-Z0-9]+$/)

Error: ANDROID_HOME is not set and "android" command not in your PATH. You must fulfill at least one of these conditions.

Android path set in linux:

$export ANDROID_HOME=/usr/lib/android-sdk-linux
$export PATH=$PATH:$ANDROID_HOME/tools
$export PATH=$PATH:$ANDROID_HOME/platforms-tools


$cordova run android

Date object to Calendar [Java]

Calendar tCalendar = Calendar.getInstance();

date is a java.util.Date object. You may use Calendar.getInstance() as well to obtain the Calendar instance(much more efficient).

How to use aria-expanded="true" to change a css property

li a[aria-expanded="true"] span{_x000D_
    color: red;_x000D_
<li class="active">_x000D_
    <a href="#3a" class="btn btn-default btn-lg" data-toggle="tab" aria-expanded="true">_x000D_
        <span class="network-name">Google+</span>_x000D_
<li class="active">_x000D_
    <a href="#3a" class="btn btn-default btn-lg" data-toggle="tab" aria-expanded="false">_x000D_
        <span class="network-name">Google+</span>_x000D_

li a[aria-expanded="true"]{_x000D_
    background: yellow;_x000D_
<li class="active">_x000D_
    <a href="#3a" class="btn btn-default btn-lg" data-toggle="tab" aria-expanded="true">_x000D_
        <span class="network-name">Google+</span>_x000D_
<li class="active">_x000D_
    <a href="#3a" class="btn btn-default btn-lg" data-toggle="tab" aria-expanded="false">_x000D_
        <span class="network-name">Google+</span>_x000D_

Toggle visibility property of div

There is another way of doing this with just JavaScript. All you have to do is toggle the visibility based on the current state of the DIV's visibility in CSS.


function toggleVideo() {
     var e = document.getElementById('video-over');

     if( == 'visible') {
 = 'hidden';
     } else if( == 'hidden') {
 = 'visible';

How is the java memory pool divided?

The Heap is divided into young and old generations as follows :

Young Generation: It is a place where an object lived for a short period and it is divided into two spaces:

  • Eden Space: When object created using new keyword memory allocated on this space.
  • Survivor Space (S0 and S1): This is the pool which contains objects which have survived after minor java garbage collection from Eden space.

Old Generation: This pool basically contains tenured and virtual (reserved) space and will be holding those objects which survived after garbage collection from the Young Generation.

  • Tenured Space: This memory pool contains objects which survived after multiple garbage collection means an object which survived after garbage collection from Survivor space.

enter image description here


Let's imagine our application has just started.

So at this point all three of these spaces are empty (Eden, S0, S1).

Whenever a new object is created it is placed in the Eden space.

When the Eden space gets full then the garbage collection process (minor GC) will take place on the Eden space and any surviving objects are moved into S0.

Our application then continues running add new objects are created in the Eden space the next time that the garbage collection process runs it looks at everything in the Eden space and in S0 and any objects that survive get moved into S1.

PS: Based on the configuration that how much time object should survive in Survivor space, the object may also move back and forth to S0 and S1 and then reaching the threshold objects will be moved to old generation heap space.

Convert Pixels to Points

WPF converts points to pixels with the System.Windows.FontSizeConverter. The FontSizeConverter uses the System.Windows.LengthConverter. The LengthConverter uses the factor 1.333333333333333333 to convert from points (p) to pixels (x): x = p * 1.3333333333333333

How and when to use ‘async’ and ‘await’

The async is used with a function to makes it into an asynchronous function. The await keyword is used to invoke an asynchronous function synchronously. The await keyword holds the JS engine execution until promise is resolved.

We should use async & await only when we want the result immediately. Maybe the result is being returned from the function or getting used in the next line.

Follow this blog, It is very well written in simple word

Configuring user and password with Git Bash

I wrote the answer inside this link;

Still, I am sharing it here as well.

Change username and email global

git config --global "<username>"
git config --global "<email>"

Change username and email for current repo

git config "<username>" --replace-all
git config "<email>" --replace-all

String replacement in java, similar to a velocity template

I use GroovyShell in java to parse template with Groovy GString:

Binding binding = new Binding();
GroovyShell gs = new GroovyShell(binding);
// this JSONObject can also be replaced by any Java Object
JSONObject obj = new JSONObject();
obj.put("key", "value");
binding.setProperty("obj", obj)
String str = "${obj.key}";
String exp = String.format("\"%s\".toString()", str);
String res = (String) gs.evaluate(exp);
// value

How can I introduce multiple conditions in LIKE operator?

This is a good use of a temporary table.

  pattern VARCHAR(20)

INSERT INTO patterns VALUES ('ABC%'), ('XYZ%'), ('PQR%');

SELECT t.* FROM tbl t JOIN patterns p ON (t.col LIKE p.pattern);

In the example patterns, there's no way col could match more than one pattern, so you can be sure you'll see each row of tbl at most once in the result. But if your patterns are such that col could match more than one, you should use the DISTINCT query modifier.

SELECT DISTINCT t.* FROM tbl t JOIN patterns p ON (t.col LIKE p.pattern);

Bootstrap: wider input field

I am going to assume you were having the same issue I was. Even though you specify larger sizes for the TextBox and mark it as important, the box would not get larger. That is likely because in your site.css file the MaxWidth is being set to 280px.

Add a style attribute to your input to remove the MaxWidth like this:

<input type="text"  style="max-width:none !important" class="input-medium">

Delete a row in DataGridView Control in VB.NET

Assuming you are using Windows forms, you could allow the user to select a row and in the delete key click event. It is recommended that you allow the user to select 1 row only and not a group of rows (myDataGridView.MultiSelect = false)

Private Sub pbtnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click

        If myDataGridView.SelectedRows.Count > 0 Then
            'you may want to add a confirmation message, and if the user confirms delete
            MessageBox.Show("Select 1 row before you hit Delete")
        End If

    End Sub

Note that this will not delete the row form the database until you perform the delete in the database.

AngularJS does not send hidden field value

I use a classical javascript to set value to hidden input

$scope.SetPersonValue = function (PersonValue)
    document.getElementById('TypeOfPerson').value = PersonValue;
    if (PersonValue != 'person')
        document.getElementById('Discount').checked = false;
        $scope.isCollapsed = true;
        $scope.isCollapsed = false;

Persist javascript variables across pages?

I would recommend you to give a look to this library:

I really like it, it supports a variety of storage backends (from cookies to HTML5 storage, Gears, Flash, and more...), its usage is really transparent, you don't have to know or care which backend is used the library will choose the right storage backend depending on the browser capabilities.

How to create dynamic href in react render function?

Could you please try this ?

Create another item in post such as then assign the link to it before send post to the render function. = '/posts/+ id.toString();

So, the above render function should be following instead.

return <li key={}><a href={}>{post.title}</a></li>

How can I make my layout scroll both horizontally and vertically?

You can do this by using below code


Calculating Page Load Time In JavaScript

Why so complicated? When you can do:

var loadTime = window.performance.timing.domContentLoadedEventEnd- window.performance.timing.navigationStart;

If you need more times check out the window.performance object:


Will show you the timing object:

connectEnd                 Time when server connection is finished.
connectStart               Time just before server connection begins.
domComplete                Time just before document readiness completes.
domContentLoadedEventEnd   Time after DOMContentLoaded event completes.
domContentLoadedEventStart Time just before DOMContentLoaded starts.
domInteractive             Time just before readiness set to interactive.
domLoading                 Time just before readiness set to loading.
domainLookupEnd            Time after domain name lookup.
domainLookupStart          Time just before domain name lookup.
fetchStart                 Time when the resource starts being fetched.
loadEventEnd               Time when the load event is complete.
loadEventStart             Time just before the load event is fired.
navigationStart            Time after the previous document begins unload.
redirectCount              Number of redirects since the last non-redirect.
redirectEnd                Time after last redirect response ends.
redirectStart              Time of fetch that initiated a redirect.
requestStart               Time just before a server request.
responseEnd                Time after the end of a response or connection.
responseStart              Time just before the start of a response.
timing                     Reference to a performance timing object.
navigation                 Reference to performance navigation object.
performance                Reference to performance object for a window.
type                       Type of the last non-redirect navigation event.
unloadEventEnd             Time after the previous document is unloaded.
unloadEventStart           Time just before the unload event is fired.

Browser Support

More Info

SQL JOIN vs IN performance?

The optimizer should be smart enough to give you the same result either way for normal queries. Check the execution plan and they should give you the same thing. If they don't, I would normally consider the JOIN to be faster. All systems are different, though, so you should profile the code on your system to be sure.

Difference between 3NF and BCNF in simple terms (must be able to explain to an 8-year old)

This is an old question with valuable answers, but I was still a bit confused until I found a real life example that shows the issue with 3NF. Maybe not suitable for an 8-year old child but hope it helps.

Tomorrow I'll meet the teachers of my eldest daughter in one of those quarterly parent/teachers meetings. Here's what my diary looks like (names and rooms have been changed):

Teacher   | Date             | Room
Mr Smith  | 2018-12-18 18:15 | A12 
Mr Jones  | 2018-12-18 18:30 | B10 
Ms Doe    | 2018-12-18 18:45 | C21 
Ms Rogers | 2018-12-18 19:00 | A08 

There's only one teacher per room and they never move. If you have a look, you'll see that: (1) for every attribute Teacher, Date, Room, we have only one value per row. (2) super-keys are: (Teacher, Date, Room), (Teacher, Date) and (Date, Room) and candidate keys are obviously (Teacher, Date) and (Date, Room).

(Teacher, Room) is not a superkey because I will complete the table next quarter and I may have a row like this one (Mr Smith did not move!):

Teacher  | Date             | Room
---------|------------------| ----
Mr Smith | 2019-03-19 18:15 | A12

What can we conclude? (1) is an informal but correct formulation of 1NF. From (2) we see that there is no "non prime attribute": 2NF and 3NF are given for free.

My diary is 3NF. Good! No. Not really because no data modeler would accept this in a DB schema. The Room attribute is dependant on the Teacher attribute (again: teachers do not move!) but the schema does not reflect this fact. What would a sane data modeler do? Split the table in two:

Teacher   | Date
Mr Smith  | 2018-12-18 18:15
Mr Jones  | 2018-12-18 18:30
Ms Doe    | 2018-12-18 18:45
Ms Rogers | 2018-12-18 19:00


Teacher   | Room
Mr Smith  | A12
Mr Jones  | B10
Ms Doe    | C21
Ms Rogers | A08

But 3NF does not deal with prime attributes dependencies. This is the issue: 3NF compliance is not enough to ensure a sound table schema design under some circumstances.

With BCNF, you don't care if the attribute is a prime attribute or not in 2NF and 3NF rules. For every non trivial dependency (subsets are obviously determined by their supersets), the determinant is a complete super key. In other words, nothing is determined by something else than a complete super key (excluding trivial FDs). (See other answers for formal definition).

As soon as Room depends on Teacher, Room must be a subset of Teacher (that's not the case) or Teacher must be a super key (that's not the case in my diary, but thats the case when you split the table).

To summarize: BNCF is more strict, but in my opinion easier to grasp, than 3NF:

  • in most of cases, BCNF is identical to 3NF;
  • in other cases, BCNF is what you think/hope 3NF is.

Use string contains function in oracle SQL query

By lines I assume you mean rows in the table person. What you're looking for is:

from   person p
where LIKE '%A%'; --contains the character 'A'

The above is case sensitive. For a case insensitive search, you can do:

from   person p
where  UPPER( LIKE '%A%'; --contains the character 'A' or 'a'

For the special character, you can do:

from   person p
where LIKE '%'||chr(8211)||'%'; --contains the character chr(8211)

The LIKE operator matches a pattern. The syntax of this command is described in detail in the Oracle documentation. You will mostly use the % sign as it means match zero or more characters.

I can't find my git.exe file in my Github folder

run github that you downloaded, click tools and options symbol(top right), click about github for windows and then open the debug log. under DIAGNOSTICS look for Git Executable Exists:

How to edit my Excel dropdown list?

Attribute_Brands is a named range.

On any worksheet (tab) press F5 and type Attribute_Brands into the reference box and click on the OK button.

This will take you to the named range.

The data in it can be updated by typing new values into the cells.

The named range can be altered via the 'Insert - Name - Define' menu.

How to completely remove Python from a Windows machine?

Almost all of the python files should live in their respective folders (C:\Python26 and C:\Python27). Some installers (ActiveState) will also associate .py* files and add the python path to %PATH% with an install if you tick the "use this as the default installation" box.

Create thumbnail image

You have to use GetThumbnailImage method in the Image class:

Here's a rough example that takes an image file and makes a thumbnail image from it, then saves it back to disk.

Image image = Image.FromFile(fileName);
Image thumb = image.GetThumbnailImage(120, 120, ()=>false, IntPtr.Zero);
thumb.Save(Path.ChangeExtension(fileName, "thumb"));

It is in the System.Drawing namespace (in System.Drawing.dll).


If the Image contains an embedded thumbnail image, this method retrieves the embedded thumbnail and scales it to the requested size. If the Image does not contain an embedded thumbnail image, this method creates a thumbnail image by scaling the main image.

Important: the remarks section of the Microsoft link above warns of certain potential problems:

The GetThumbnailImage method works well when the requested thumbnail image has a size of about 120 x 120 pixels. If you request a large thumbnail image (for example, 300 x 300) from an Image that has an embedded thumbnail, there could be a noticeable loss of quality in the thumbnail image.

It might be better to scale the main image (instead of scaling the embedded thumbnail) by calling the DrawImage method.

Examples of Algorithms which has O(1), O(n log n) and O(log n) complexities

You can add following algorithms to your list:

O(1) - Determining if a number is even or odd; Working with HashMap

O(logN) - computing x^N,

O(N Log N) - Longest increasing subsequence

How to display my location on Google Maps for Android API v2

The API Guide has it all wrong (really Google?). With Maps API v2 you do not need to enable a layer to show yourself, there is a simple call to the GoogleMaps instance you created with your map.

Google Documentation

The actual documentation that Google provides gives you your answer. You just need to

If you are using Kotlin

// map is a GoogleMap object
map.isMyLocationEnabled = true

If you are using Java

// map is a GoogleMap object

and watch the magic happen.

Just make sure that you have location permission and requested it at runtime on API Level 23 (M) or above

Make div scrollable

You need to remove the




and then add

overflow: auto;

property to the class of the required div

Finding the id of a parent div using Jquery

JQUery has a .parents() method for moving up the DOM tree you can start there.

If you're interested in doing this a more semantic way I don't think using the REL attribute on a button is the best way to semantically define "this is the answer" in your code. I'd recommend something along these lines:

<p id="question1">
    <label for="input1">Volume =</label> 
    <input type="text" name="userInput1" id="userInput1" />
    <button type="button">Check answer</button>
    <input type="hidden" id="answer1" name="answer1" value="3.93e-6" />


$("button").click(function () {
    var correctAnswer = $(this).parent().siblings("input[type=hidden]").val();
    var userAnswer = $(this).parent().siblings("input[type=text]").val();
    validate(userAnswer, correctAnswer);

Not quite sure how your validate and feedback are working, but you get the idea.

SQL - Query to get server's IP address

The server might have multiple IP addresses that it is listening on. If your connection has the VIEW SERVER STATE server permission granted to it, you can run this query to get the address you have connected to SQL Server:

SELECT dec.local_net_address
FROM sys.dm_exec_connections AS dec
WHERE dec.session_id = @@SPID;

This solution does not require you to shell out to the OS via xp_cmdshell, which is a technique that should be disabled (or at least strictly secured) on a production server. It may require you to grant VIEW SERVER STATE to the appropriate login, but that is a far smaller security risk than running xp_cmdshell.

The technique mentioned by GilM for the server name is the preferred one:


Input jQuery get old value before onchange and get value after on change

I found this question today, but I'm not sure why was this made so complicated rather than implementing it simply like:

var input = $('#target');
var inputVal = input.val();
input.on('change', function() {
  console.log('Current Value: ', $(this).val());
  console.log('Old Value: ', inputVal);
  inputVal = $(this).val();

If you want to target multiple inputs then, use each function:

$('input').each(function() {
  var inputVal = $(this).val();
  $(this).on('change', function() {
    console.log('Current Value: ',$(this).val());
    console.log('Old Value: ', inputVal);
    inputVal = $(this).val();

codeigniter model error: Undefined property

function user() { 



=> class name is User, construct name is User.

function User() { 



VB.NET Empty String Array

Something like:

Dim myArray(9) as String

Would give you an array of 10 String references (each pointing to Nothing).

If you're not sure of the size at declaration time, you can declare a String array like this:

Dim myArray() as String

And then you can point it at a properly-sized array of Strings later:

ReDim myArray(9) as String

ZombieSheep is right about using a List if you don't know the total size and you need to dynamically populate it. In VB.NET that would be:

Dim myList as New List(Of String)

And then to get an array from that List:



Thanks for the correction.

Convert json data to a html table

Check out JSON2HTML plugin for jQuery. It allows you to specify a transform that would convert your JSON object to HTML template. Use builder on to get json transform object for any desired html template. In your case, it would be a table with row having following transform.


var transform = {"tag":"table", "children":[

var data = [


Get the number of rows in a HTML table


var count = $('#gvPerformanceResult tr').length;

keyCode values for numeric keypad?

Yes, they are different and while many people have made a great suggestion of using console.log to see for yourself. However, I didn't see anyone mention event.location that you can use that to determine if the number is coming from the keypad event.location === 3 vs the top of the main keyboard / general keys event.location === 0. This approach would be best suited for when you need to generally determine if keystrokes are coming from a region of the keyboard or not, event.key is likely better for the specific keys.

Git add and commit in one command

To keep it in one line use:

git add . && git commit -am "comment"

This line will add and commit all changed and added files to repository.

Generating random numbers with normal distribution in Excel

Use the NORMINV function together with RAND():


To keep your set of random values from changing, select all the values, copy them, and then paste (special) the values back into the same range.

Sample output (column A), 500 numbers generated with this formula:

enter image description here

No String-argument constructor/factory method to deserialize from String value ('')

This exception says that you are trying to deserialize the object "Address" from string "\"\"" instead of an object description like "{…}". The deserializer can't find a constructor of Address with String argument. You have to replace "" by {} to avoid this error.

Can pandas automatically recognize dates?

Perhaps the pandas interface has changed since @Rutger answered, but in the version I'm using (0.15.2), the date_parser function receives a list of dates instead of a single value. In this case, his code should be updated like so:

dateparse = lambda dates: [pd.datetime.strptime(d, '%Y-%m-%d %H:%M:%S') for d in dates]

df = pd.read_csv(infile, parse_dates=['datetime'], date_parser=dateparse)

Android Studio marks R in red with error message "cannot resolve symbol R", but build succeeds

this causes mainly because of errors in xml file, check your latest xml changes and rebuild it, same issue with me.

How do I return multiple values from a function in C?

Since one of your result types is a string (and you're using C, not C++), I recommend passing pointers as output parameters. Use:

void foo(int *a, char *s, int size);

and call it like this:

int a;
char *s = (char *)malloc(100); /* I never know how much to allocate :) */
foo(&a, s, 100);

In general, prefer to do the allocation in the calling function, not inside the function itself, so that you can be as open as possible for different allocation strategies.

Does C# have extension properties?

For the moment it is still not supported out of the box by Roslyn compiler ...

Until now, the extension properties were not seen as valuable enough to be included in the previous versions of C# standard. C# 7 and C# 8.0 have seen this as proposal champion but it wasn't released yet, most of all because even if there is already an implementation, they want to make it right from the start.

But it will ...

There is an extension members item in the C# 7 work list so it may be supported in the near future. The current status of extension property can be found on Github under the related item.

However, there is an even more promising topic which is the "extend everything" with a focus on especially properties and static classes or even fields.

Moreover you can use a workaround

As specified in this article, you can use the TypeDescriptor capability to attach an attribute to an object instance at runtime. However, it is not using the syntax of the standard properties.
It's a little bit different from just syntactic sugar adding a possibility to define an extended property like
string Data(this MyClass instance) as an alias for extension method
string GetData(this MyClass instance) as it stores data into the class.

I hope that C#7 will provide a full featured extension everything (properties and fields), however on that point, only time will tell.

And feel free to contribute as the software of tomorrow will come from the community.

Update: August 2016

As dotnet team published what's new in C# 7.0 and from a comment of Mads Torgensen:

Extension properties: we had a (brilliant!) intern implement them over the summer as an experiment, along with other kinds of extension members. We remain interested in this, but it’s a big change and we need to feel confident that it’s worth it.

It seems that extension properties and other members, are still good candidates to be included in a future release of Roslyn, but maybe not the 7.0 one.

Update: May 2017

The extension members has been closed as duplicate of extension everything issue which is closed too. The main discussion was in fact about Type extensibility in a broad sense. The feature is now tracked here as a proposal and has been removed from 7.0 milestone.

Update: August, 2017 - C# 8.0 proposed feature

While it still remains only a proposed feature, we have now a clearer view of what would be its syntax. Keep in mind that this will be the new syntax for extension methods as well:

public interface IEmployee 
    public decimal Salary { get; set; }

public class Employee
    public decimal Salary { get; set; }

public extension MyPersonExtension extends Person : IEmployee
    private static readonly ConditionalWeakTable<Person, Employee> _employees = 
        new ConditionalWeakTable<Person, Employee>();

    public decimal Salary
            // `this` is the instance of Person
            return _employees.GetOrCreate(this).Salary; 
            Employee employee = null;
            if (!_employees.TryGetValue(this, out employee)
                employee = _employees.GetOrCreate(this);
            employee.Salary = value;

IEmployee person = new Person();
var salary = person.Salary;

Similar to partial classes, but compiled as a separate class/type in a different assembly. Note you will also be able to add static members and operators this way. As mentioned in Mads Torgensen podcast, the extension won't have any state (so it cannot add private instance members to the class) which means you won't be able to add private instance data linked to the instance. The reason invoked for that is it would imply to manage internally dictionaries and it could be difficult (memory management, etc...). For this, you can still use the TypeDescriptor/ConditionalWeakTable technique described earlier and with the property extension, hides it under a nice property.

Syntax is still subject to change as implies this issue. For example, extends could be replaced by for which some may feel more natural and less java related.

Update December 2018 - Roles, Extensions and static interface members

Extension everything didn't make it to C# 8.0, because of some of drawbacks explained as the end of this GitHub ticket. So, there was an exploration to improve the design. Here, Mads Torgensen explains what are roles and extensions and how they differs:

Roles allow interfaces to be implemented on specific values of a given type. Extensions allow interfaces to be implemented on all values of a given type, within a specific region of code.

It can be seen at a split of previous proposal in two use cases. The new syntax for extension would be like this:

public extension ULongEnumerable of ulong
    public IEnumerator<byte> GetEnumerator()
        for (int i = sizeof(ulong); i > 0; i--)
            yield return unchecked((byte)(this >> (i-1)*8));

then you would be able to do this:

foreach (byte b in 0x_3A_9E_F1_C5_DA_F7_30_16ul)

And for a static interface:

public interface IMonoid<T> where T : IMonoid<T>
    static T operator +(T t1, T t2);
    static T Zero { get; }

Add an extension property on int and treat the int as IMonoid<int>:

public extension IntMonoid of int : IMonoid<int>
    public static int Zero => 0;

Setting unique Constraint with fluent API?

As an addition to Yorro's answer, it can also be done by using attributes.

Sample for int type unique key combination:

[Index("IX_UniqueKeyInt", IsUnique = true, Order = 1)]
public int UniqueKeyIntPart1 { get; set; }

[Index("IX_UniqueKeyInt", IsUnique = true, Order = 2)]
public int UniqueKeyIntPart2 { get; set; }

If the data type is string, then MaxLength attribute must be added:

[Index("IX_UniqueKeyString", IsUnique = true, Order = 1)]
public string UniqueKeyStringPart1 { get; set; }

[Index("IX_UniqueKeyString", IsUnique = true, Order = 2)]
public string UniqueKeyStringPart2 { get; set; }

If there is a domain/storage model separation concern, using Metadatatype attribute/class can be an option:

A quick console app example:

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity;

namespace EFIndexTest
    class Program
        static void Main(string[] args)
            using (var context = new AppDbContext())
                var newUser = new User { UniqueKeyIntPart1 = 1, UniqueKeyIntPart2 = 1, UniqueKeyStringPart1 = "A", UniqueKeyStringPart2 = "A" };

    public class User
        public int Id { get; set; }
        public int UniqueKeyIntPart1 { get; set; }
        public int UniqueKeyIntPart2 { get; set; }
        public string UniqueKeyStringPart1 { get; set; }
        public string UniqueKeyStringPart2 { get; set; }

    public class UserMetadata
        [Index("IX_UniqueKeyInt", IsUnique = true, Order = 1)]
        public int UniqueKeyIntPart1 { get; set; }

        [Index("IX_UniqueKeyInt", IsUnique = true, Order = 2)]
        public int UniqueKeyIntPart2 { get; set; }

        [Index("IX_UniqueKeyString", IsUnique = true, Order = 1)]
        public string UniqueKeyStringPart1 { get; set; }

        [Index("IX_UniqueKeyString", IsUnique = true, Order = 2)]
        public string UniqueKeyStringPart2 { get; set; }

    public class AppDbContext : DbContext
        public virtual DbSet<User> UserSet { get; set; }

Run cron job only if it isn't already running

Consider using pgrep (if available) rather than ps piped through grep if you're going to go that route. Though, personally, I've got a lot of mileage out of scripts of the form

  call script_that_must_run
  sleep 5

Though this can fail and cron jobs are often the best way for essential stuff. Just another alternative.

How to retrieve checkboxes values in jQuery

 function updateTextArea() {         
     var allVals = $('#c_b :checked').map(function() {
       return $(this).val();
 $(function() {
   $('#c_b input').click(updateTextArea);

How to center an element horizontally and vertically

Below is the Flex-box approach to get desired result

<!DOCTYPE html>_x000D_
  <meta charset="utf-8">_x000D_
  <meta name="viewport" content="width=device-width">_x000D_
  <title>Flex-box approach</title>_x000D_
    display: -webkit-flex;_x000D_
    display: flex;_x000D_
    width: 500px;_x000D_
    height: 250px;_x000D_
    background-color: grey;_x000D_
    margin: 0 auto;_x000D_
    width: 200px;_x000D_
    height: 200px;_x000D_
    margin: 20px;_x000D_
    background-color: yellow;_x000D_
    margin: 0 auto;_x000D_
    display: inline; /*for vertically aligning */_x000D_
    top: 9%;         /*for vertically aligning */_x000D_
    position: relative; /*for vertically aligning */_x000D_
    <div class="tabs">_x000D_
        <div class="f">first</div>_x000D_
        <div class="f">second</div>        _x000D_

Push git commits & tags simultaneously

Maybe this helps someone:

git tag 0.0.1                    # creates tag locally     
git push origin 0.0.1            # pushes tag to remote

git tag --delete 0.0.1           # deletes tag locally    
git push --delete origin 0.0.1   # deletes remote tag

How to check if an object is defined?

If a class type is not defined, you'll get a compiler error if you try to use the class, so in that sense you should have to check.

If you have an instance, and you want to ensure it's not null, simply check for null:

if (value != null)
    // it's not null. 

Python "SyntaxError: Non-ASCII character '\xe2' in file"

I had the same issue but it was because I copied and pasted the string as it is. Later when I manually typed the string as it is the error vanished.

I had the error due to the - sign. When I replaced it with manually inputting a - the error was solved.

Copied string 10 + 3 * 5/(16 - 4)

Manually typed string 10 + 3 * 5/(16 - 4)

you can clearly see there is a bit of difference between both the hyphens.

I think it's because of the different formatting used by different OS or maybe just different software.

Removing duplicates from rows based on specific columns in an RDD/Spark DataFrame

The below programme will help you drop duplicates on whole , or if you want to drop duplicates based on certain columns , you can even do that:

import org.apache.spark.sql.SparkSession

object DropDuplicates {
def main(args: Array[String]) {
val spark =

import spark.implicits._

// create an RDD of tuples with some data
val custs = Seq(
  (1, "Widget Co", 120000.00, 0.00, "AZ"),
  (2, "Acme Widgets", 410500.00, 500.00, "CA"),
  (3, "Widgetry", 410500.00, 200.00, "CA"),
  (4, "Widgets R Us", 410500.00, 0.0, "CA"),
  (3, "Widgetry", 410500.00, 200.00, "CA"),
  (5, "Ye Olde Widgete", 500.00, 0.0, "MA"),
  (6, "Widget Co", 12000.00, 10.00, "AZ")
val customerRows = spark.sparkContext.parallelize(custs, 4)

// convert RDD of tuples to DataFrame by supplying column names
val customerDF = customerRows.toDF("id", "name", "sales", "discount", "state")

println("*** Here's the whole DataFrame with duplicates")


// drop fully identical rows
val withoutDuplicates = customerDF.dropDuplicates()

println("*** Now without duplicates")

// drop fully identical rows
val withoutPartials = customerDF.dropDuplicates(Seq("name", "state"))

println("*** Now without partial duplicates too")


Where to find extensions installed folder for Google Chrome on Mac?

The default locations of Chrome's profile directory are defined at For Chrome on Mac, it's

~/Library/Application\ Support/Google/Chrome/Default

The actual location can be different, by setting the --user-data-dir=path/to/directory flag.
If only one user is registered in Chrome, look in the Default/Extensions subdirectory. Otherwise, look in the <profile user name>/Extensions directory.

If that didn't help, you can always do a custom search.

  1. Go to chrome://extensions/, and find out the ID of an extension (32 lowercase letters) (if not done already, activate "Developer mode" first).

  2. Open the terminal, cd to the directory which is most likely a parent of your Chrome profile (if unsure, try ~ then /).

  3. Run find . -type d -iname "<EXTENSION ID HERE>", for example:

    find . -type d -iname jifpbeccnghkjeaalbbjmodiffmgedin


    ./Library/Application Support/Google/Chrome/Default/Extensions/jifpbeccnghkjeaalbbjmodiffmgedin

Angular 4: InvalidPipeArgument: '[object Object]' for pipe 'AsyncPipe'

You should add the pipe to the interpolation and not to the ngFor

  li(*ngFor='let movie of (movies)') ///////////removed here///////////////////
    | {{ movie.title | async }}

Reference docs

Oracle timestamp data type

The number in parentheses specifies the precision of fractional seconds to be stored. So, (0) would mean don't store any fraction of a second, and use only whole seconds. The default value if unspecified is 6 digits after the decimal separator.

So an unspecified value would store a date like:


And specifying (0) stores only:

TIMESTAMP(0) 24-JAN-2012 08.00.05 AM

See Oracle documentation on data types.

How to link to apps on the app store

Simply change 'itunes' to 'phobos' in the app link.

Now it will open the App Store directly

How can I set an SQL Server connection string?

We can simply connect to the database like this:


For example:

string connectionString = @"uid=spacecraftU1;pwd=Appolo11;
SqlConnection con = new SqlConnection(connectionString);

Read entire file in Scala?

You do not need to parse every single line and then concatenate them again...


I prefer to use this:

import{BufferedSource, Codec, Source}
import scala.util.Try

def readFileUtf8(path: String): Try[String] = Try {
  val source: BufferedSource = Source.fromFile(path)(Codec.UTF8)
  val content = source.mkString

TypeError: 'module' object is not callable

Add to the main in YourClassParentDir, e.g.:

from .YourClass import YourClass

Then, you will have an instance of your class ready when you import it into another script:

from YourClassParentDir import YourClass

What's the difference between "&nbsp;" and " "?

&nbsp; is stackable, meaning you can create multiple spaces all together.

HTML will only parse one space '' and it drops the rest...

If you want five spaces, you would place 5 x &nbsp;

How to access form methods and controls from a class in C#?

Another solution would be to pass the textbox (or control you want to modify) into the method that will manipulate it as a parameter.

public partial class Form1 : Form
    public Form1()

    private void button1_Click(object sender, EventArgs e)
        TestClass test = new TestClass();

public class TestClass
    public void ModifyText(TextBox textBox)
        textBox.Text = "New text";

How to get the previous url using PHP

$_SERVER['HTTP_REFERER'] will give you incomplete url.

If you want, $_SERVER['HTTP_REFERER'] will give you only.

How to create custom exceptions in Java?

public class MyException extends Exception {
        // special exception code goes here

Throw it as:

 throw new MyException ("Something happened")

Catch as:

catch (MyException e)
   // something

Error #2032: Stream Error

From a quick google search it seems that the problem is a file or url couldn't be found be the HTTPservice.

Here are the links where I found this information:

How to iterate through LinkedHashMap with lists as values

for (Map.Entry<String, ArrayList<String>> entry : test1.entrySet()) {
    String key = entry.getKey();
    ArrayList<String> value = entry.getValue();
    // now work with key and value...

By the way, you should really declare your variables as the interface type instead, such as Map<String, List<String>>.

Remove empty space before cells in UITableView

If you are doing this on iOS 11, automaticallyAdjustsScrollViewInsets won't work as it is deprecated, the following code worked for me as per the answer in this post:

        if #available(iOS 11.0, *) {
            tblView.contentInsetAdjustmentBehavior = .never
        } else {
            automaticallyAdjustsScrollViewInsets = false

Hope this helps.

Markdown and including multiple files

IMHO, You can get your result by concatenating your input *.md files like:

$ pandoc -s -o outputDoc.pdf

selenium get current url after loading a page

Page 2 is in a new tab/window ? If it's this, use the code bellow :

try {

    String winHandleBefore = driver.getWindowHandle();

    for(String winHandle : driver.getWindowHandles()){
        String act = driver.getCurrentUrl();
    }catch(Exception e){

Lookup City and State by Zip Google Geocode Api

function getCityState($zip, $blnUSA = true) {
    $url = "" . $zip . "&sensor=true";

    $address_info = file_get_contents($url);
    $json = json_decode($address_info);
    $city = "";
    $state = "";
    $country = "";
    if (count($json->results) > 0) {
        //break up the components
        $arrComponents = $json->results[0]->address_components;

        foreach($arrComponents as $index=>$component) {
            $type = $component->types[0];

            if ($city == "" && ($type == "sublocality_level_1" || $type == "locality") ) {
                $city = trim($component->short_name);
            if ($state == "" && $type=="administrative_area_level_1") {
                $state = trim($component->short_name);
            if ($country == "" && $type=="country") {
                $country = trim($component->short_name);

                if ($blnUSA && $country!="US") {
                    $city = "";
                    $state = "";
            if ($city != "" && $state != "" && $country != "") {
                //we're done
    $arrReturn = array("city"=>$city, "state"=>$state, "country"=>$country);


Where are include files stored - Ubuntu Linux, GCC

See here: Search Path


#include <stdio.h>

When the include file is in brackets the preprocessor first searches in paths specified via the -I flag. Then it searches the standard include paths (see the above link, and use the -v flag to test on your system).

#include "myFile.h"

When the include file is in quotes the preprocessor first searches in the current directory, then paths specified by -iquote, then -I paths, then the standard paths.

-nostdinc can be used to prevent the preprocessor from searching the standard paths at all.

Environment variables can also be used to add search paths.

When compiling if you use the -v flag you can see the search paths used.

Is floating point math broken?

My answer is quite long, so I've split it into three sections. Since the question is about floating point mathematics, I've put the emphasis on what the machine actually does. I've also made it specific to double (64 bit) precision, but the argument applies equally to any floating point arithmetic.


An IEEE 754 double-precision binary floating-point format (binary64) number represents a number of the form

value = (-1)^s * (1.m51m50...m2m1m0)2 * 2e-1023

in 64 bits:

  • The first bit is the sign bit: 1 if the number is negative, 0 otherwise1.
  • The next 11 bits are the exponent, which is offset by 1023. In other words, after reading the exponent bits from a double-precision number, 1023 must be subtracted to obtain the power of two.
  • The remaining 52 bits are the significand (or mantissa). In the mantissa, an 'implied' 1. is always2 omitted since the most significant bit of any binary value is 1.

1 - IEEE 754 allows for the concept of a signed zero - +0 and -0 are treated differently: 1 / (+0) is positive infinity; 1 / (-0) is negative infinity. For zero values, the mantissa and exponent bits are all zero. Note: zero values (+0 and -0) are explicitly not classed as denormal2.

2 - This is not the case for denormal numbers, which have an offset exponent of zero (and an implied 0.). The range of denormal double precision numbers is dmin = |x| = dmax, where dmin (the smallest representable nonzero number) is 2-1023 - 51 (˜ 4.94 * 10-324) and dmax (the largest denormal number, for which the mantissa consists entirely of 1s) is 2-1023 + 1 - 2-1023 - 51 (˜ 2.225 * 10-308).

Turning a double precision number to binary

Many online converters exist to convert a double precision floating point number to binary (e.g. at, but here is some sample C# code to obtain the IEEE 754 representation for a double precision number (I separate the three parts with colons (:):

public static string BinaryRepresentation(double value)
    long valueInLongType = BitConverter.DoubleToInt64Bits(value);
    string bits = Convert.ToString(valueInLongType, 2);
    string leadingZeros = new string('0', 64 - bits.Length);
    string binaryRepresentation = leadingZeros + bits;

    string sign = binaryRepresentation[0].ToString();
    string exponent = binaryRepresentation.Substring(1, 11);
    string mantissa = binaryRepresentation.Substring(12);

    return string.Format("{0}:{1}:{2}", sign, exponent, mantissa);

Getting to the point: the original question

(Skip to the bottom for the TL;DR version)

Cato Johnston (the question asker) asked why 0.1 + 0.2 != 0.3.

Written in binary (with colons separating the three parts), the IEEE 754 representations of the values are:

0.1 => 0:01111111011:1001100110011001100110011001100110011001100110011010
0.2 => 0:01111111100:1001100110011001100110011001100110011001100110011010

Note that the mantissa is composed of recurring digits of 0011. This is key to why there is any error to the calculations - 0.1, 0.2 and 0.3 cannot be represented in binary precisely in a finite number of binary bits any more than 1/9, 1/3 or 1/7 can be represented precisely in decimal digits.

Also note that we can decrease the power in the exponent by 52 and shift the point in the binary representation to the right by 52 places (much like 10-3 * 1.23 == 10-5 * 123). This then enables us to represent the binary representation as the exact value that it represents in the form a * 2p. where 'a' is an integer.

Converting the exponents to decimal, removing the offset, and re-adding the implied 1 (in square brackets), 0.1 and 0.2 are:

0.1 => 2^-4 * [1].1001100110011001100110011001100110011001100110011010
0.2 => 2^-3 * [1].1001100110011001100110011001100110011001100110011010
0.1 => 2^-56 * 7205759403792794 = 0.1000000000000000055511151231257827021181583404541015625
0.2 => 2^-55 * 7205759403792794 = 0.200000000000000011102230246251565404236316680908203125

To add two numbers, the exponent needs to be the same, i.e.:

0.1 => 2^-3 *  0.1100110011001100110011001100110011001100110011001101(0)
0.2 => 2^-3 *  1.1001100110011001100110011001100110011001100110011010
sum =  2^-3 * 10.0110011001100110011001100110011001100110011001100111
0.1 => 2^-55 * 3602879701896397  = 0.1000000000000000055511151231257827021181583404541015625
0.2 => 2^-55 * 7205759403792794  = 0.200000000000000011102230246251565404236316680908203125
sum =  2^-55 * 10808639105689191 = 0.3000000000000000166533453693773481063544750213623046875

Since the sum is not of the form 2n * 1.{bbb} we increase the exponent by one and shift the decimal (binary) point to get:

sum = 2^-2  * 1.0011001100110011001100110011001100110011001100110011(1)
    = 2^-54 * 5404319552844595.5 = 0.3000000000000000166533453693773481063544750213623046875

There are now 53 bits in the mantissa (the 53rd is in square brackets in the line above). The default rounding mode for IEEE 754 is 'Round to Nearest' - i.e. if a number x falls between two values a and b, the value where the least significant bit is zero is chosen.

a = 2^-54 * 5404319552844595 = 0.299999999999999988897769753748434595763683319091796875
  = 2^-2  * 1.0011001100110011001100110011001100110011001100110011

x = 2^-2  * 1.0011001100110011001100110011001100110011001100110011(1)

b = 2^-2  * 1.0011001100110011001100110011001100110011001100110100
  = 2^-54 * 5404319552844596 = 0.3000000000000000444089209850062616169452667236328125

Note that a and b differ only in the last bit; ...0011 + 1 = ...0100. In this case, the value with the least significant bit of zero is b, so the sum is:

sum = 2^-2  * 1.0011001100110011001100110011001100110011001100110100
    = 2^-54 * 5404319552844596 = 0.3000000000000000444089209850062616169452667236328125

whereas the binary representation of 0.3 is:

0.3 => 2^-2  * 1.0011001100110011001100110011001100110011001100110011
    =  2^-54 * 5404319552844595 = 0.299999999999999988897769753748434595763683319091796875

which only differs from the binary representation of the sum of 0.1 and 0.2 by 2-54.

The binary representation of 0.1 and 0.2 are the most accurate representations of the numbers allowable by IEEE 754. The addition of these representation, due to the default rounding mode, results in a value which differs only in the least-significant-bit.


Writing 0.1 + 0.2 in a IEEE 754 binary representation (with colons separating the three parts) and comparing it to 0.3, this is (I've put the distinct bits in square brackets):

0.1 + 0.2 => 0:01111111101:0011001100110011001100110011001100110011001100110[100]
0.3       => 0:01111111101:0011001100110011001100110011001100110011001100110[011]

Converted back to decimal, these values are:

0.1 + 0.2 => 0.300000000000000044408920985006...
0.3       => 0.299999999999999988897769753748...

The difference is exactly 2-54, which is ~5.5511151231258 × 10-17 - insignificant (for many applications) when compared to the original values.

Comparing the last few bits of a floating point number is inherently dangerous, as anyone who reads the famous "What Every Computer Scientist Should Know About Floating-Point Arithmetic" (which covers all the major parts of this answer) will know.

Most calculators use additional guard digits to get around this problem, which is how 0.1 + 0.2 would give 0.3: the final few bits are rounded.

Is bool a native C type?

C99 added a bool type whose semantics are fundamentally different from those of just about all integer types that had existed before in C, including user-defined and compiler-extension types intended for such purposes, and which some programs may have "type-def"ed to bool.

For example, given bool a = 0.1, b=2, c=255, d=256;, the C99 bool type would set all four objects to 1. If a C89 program used typedef unsigned char bool, the objects would receive 0, 1, 255, and 0, respectively. If it used char, the values might be as above, or c might be -1. If it had used a compiler-extension bit or __bit type, the results would likely be 0, 0, 1, 0 (treating bit in a way equivalent to an unsigned bit-field of size 1, or an unsigned integer type with one value bit).

How to take column-slices of dataframe in pandas

Its equivalent

 >>> print(df2.loc[140:160,['Relevance','Title']])
 >>> print(df2.ix[140:160,[3,7]])

Spring MVC @PathVariable with dot (.) is getting truncated

Finally I found solution in Spring Docs:

To completely disable the use of file extensions, you must set both of the following:

 useSuffixPatternMatching(false), see PathMatchConfigurer

 favorPathExtension(false), see ContentNegotiationConfigurer

Adding this to my WebMvcConfigurerAdapter implementation solved the problem:

public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {

public void configurePathMatch(PathMatchConfigurer matcher) {

clientHeight/clientWidth returning different values on different browsers

The equivalent of offsetHeight and offsetWidth in jQuery is $(window).width(), $(window).height() It's not the clientHeight and clientWidth

Can we add div inside table above every <tr>?

You could use display: table-row-group for your div.

  <div style="display: table-row-group">
  <div style="display: table-row-group">

support FragmentPagerAdapter holds reference to old fragments

Do not try to interact between fragments in ViewPager. You cannot guarantee that other fragment attached or even exists. Istead of changing actionbar title from fragment, you can do it from your activity. Use standart interface pattern for this:

public interface UpdateCallback
    void update(String name);

public class MyActivity extends FragmentActivity implements UpdateCallback
    public void update(String name)


public class MyFragment extends Fragment
    private UpdateCallback callback;

    public void onAttach(SupportActivity activity)
        callback = (UpdateCallback) activity;

    public void onDetach()
        callback = null;

    public void updateActionbar(String name)
        if(callback != null)

C# DateTime to "YYYYMMDDHHMMSS" format

using C# 6.0


Converting Float to Dollars and Cents

you said that:

`mony = float(1234.5)
print(money)      #output is 1234.5

did not work.... Have you coded exactly that way? This should work (see the little difference):

money = float(1234.5)      #next you used format without printing, nor affecting value of "money"
amountAsFormattedString = '${:,.2f}'.format(money)
print( amountAsFormattedString )

How to connect to remote Redis server?

redis-cli -h XXX.XXX.XXX.XXX -p YYYY is the IP address and yyyy is the port

EXAMPLE from my dev environment

redis-cli -h -p 30000


Host, port, password and database By default redis-cli connects to the server at port 6379. As you can guess, you can easily change this using command line options. To specify a different host name or an IP address, use -h. In order to set a different port, use -p.

redis-cli -h -p 6390 ping

how to merge 200 csv files in Python

Here is a script:

  • Concatenating csv files named SH1.csv to SH200.csv
  • Keeping the headers
import glob
import re

# Looking for filenames like 'SH1.csv' ... 'SH200.csv'
pattern = re.compile("^SH([1-9]|[1-9][0-9]|1[0-9][0-9]|200).csv$")
file_parts = [name for name in glob.glob('*.csv') if pattern.match(name)]

with open("file_merged.csv","wb") as file_merged:
    for (i, name) in enumerate(file_parts):
        with open(name, "rb") as file_part:
            if i != 0:
                next(file_part) # skip headers if not first file

MATLAB - multiple return values from a function?

Change the function that you get one single Result=[array, listp, freep]. So there is only one result to be displayed

MySQL: Insert datetime into other datetime field

for MYSQL try this

INSERT INTO table1(myDatetimeField)VALUES(STR_TO_DATE('12-01-2014 00:00:00','%m-%d-%Y %H:%i:%s');


select * from table1
output- datetime= 2014-12-01 00:00:00

How to get a value from a Pandas DataFrame and not the index and object type

import pandas as pd

dataset = pd.read_csv("data.csv")
values = list(x for x in dataset["column name"])

>>> values[0]


actually, you can just index the dataset like any old array.

import pandas as pd

dataset = pd.read_csv("data.csv")
first_value = dataset["column name"][0]

>>> print(first_value)

Use Toast inside Fragment

If you are using kotlin then the context will be already defined in the fragment. So just use that context. Try the following code to show a toast message.

Toast.makeText(context , "your_text", Toast.LENGTH_SHORT).show()

How would I get everything before a : in a string Python

Just use the split function. It returns a list, so you can keep the first element:

>>> s1.split(':')
['Username', ' How are you today?']
>>> s1.split(':')[0]

Windows recursive grep command-line

Recursive search for import word inside src folder:

> findstr /s import .\src\*

How can I make a weak protocol reference in 'pure' Swift (without @objc)

Apple uses "NSObjectProtocol" instead of "class".

public protocol UIScrollViewDelegate : NSObjectProtocol {

This also works for me and removed the errors I was seeing when trying to implement my own delegate pattern.

Column calculated from another column?

MySQL 5.7 supports computed columns. They call it "Generated Columns" and the syntax is a little weird, but it supports the same options I see in other databases.

How to import .py file from another directory?

You can add to the system-path at runtime:

import sys
sys.path.insert(0, 'path/to/your/py_file')

import py_file

This is by far the easiest way to do it.

Java Pass Method as Parameter

Example of solution with reflection, passed method must be public

import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

public class Program {
    int i;

    public static void main(String[] args) {
        Program   obj = new Program();    //some object

        try {
            Method method = obj.getClass().getMethod("target");
            repeatMethod( 5, obj, method );
        catch ( NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
            System.out.println( e ); 

    static void repeatMethod (int times, Object object, Method method)
        throws IllegalAccessException, InvocationTargetException {

        for (int i=0; i<times; i++)
    public void target() {                 //public is necessary
        System.out.println("target(): "+ ++i);

PDF to byte array and vice versa

Java 7 introduced Files.readAllBytes(), which can read a PDF into a byte[] like so:

import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.Files;

Path pdfPath = Paths.get("/path/to/file.pdf");
byte[] pdf = Files.readAllBytes(pdfPath);


Thanks Farooque for pointing out: this will work for reading any kind of file, not just PDFs. All files are ultimately just a bunch of bytes, and as such can be read into a byte[].

How to set a cookie to expire in 1 hour in Javascript?

You can write this in a more compact way:

var now = new Date();
now.setTime(now.getTime() + 1 * 3600 * 1000);
document.cookie = "name=value; expires=" + now.toUTCString() + "; path=/";

And for someone like me, who wasted an hour trying to figure out why the cookie with expiration is not set up (but without expiration can be set up) in Chrome, here is in answer:

For some strange reason Chrome team decided to ignore cookies from local pages. So if you do this on localhost, you will not be able to see your cookie in Chrome. So either upload it on the server or use another browser.

Delete data with foreign key in SQL Server table

So, you need to DELETE related rows from conflicted tables or more logical to UPDATE their FOREIGN KEY column to reference other PRIMARY KEY's from the parent table.

Also, you may want to read this article Don’t Delete – Just Don’t

Command copy exited with code 4 when building - Visual Studio restart solves it

I had the same problem. However, nothing worked for me. I solved the issue by adding

exit 0

to my code. The problem was that while I was doing copying of the files, sometimes the last file could not be found, and the bat returned a non-zero value.

Hope this helps someone!

WPF TabItem Header Styling

While searching for a way to round tabs, I found Carlo's answer and it did help but I needed a bit more. Here is what I put together, based on his work. This was done with MS Visual Studio 2015.

The Code:

<Window x:Class="MainWindow"
        Title="Rounded Tabs Example" Height="550" Width="700" WindowStartupLocation="CenterScreen" FontFamily="DokChampa" FontSize="13.333" ResizeMode="CanMinimize" BorderThickness="0">
        <DropShadowEffect Opacity="0.5"/>
    <Grid Background="#FF423C3C">
        <TabControl x:Name="tabControl" TabStripPlacement="Left" Margin="6,10,10,10" BorderThickness="3">
                <Style TargetType="{x:Type TabItem}">
                    <Setter Property="Template">
                            <ControlTemplate TargetType="{x:Type TabItem}">
                                    <Border Name="Border" Background="#FF6E6C67" Margin="2,2,-8,0" BorderBrush="Black" BorderThickness="1,1,1,1" CornerRadius="10">
                                        <ContentPresenter x:Name="ContentSite" ContentSource="Header" VerticalAlignment="Center" HorizontalAlignment="Center" Margin="2,2,12,2" RecognizesAccessKey="True"/>
                                    <Rectangle Height="100" Width="10" Margin="0,0,-10,0" Stroke="Black" VerticalAlignment="Bottom" HorizontalAlignment="Right" StrokeThickness="0" Fill="#FFD4D0C8"/>
                                    <Trigger Property="IsSelected" Value="True">
                                        <Setter Property="FontWeight" Value="Bold" />
                                        <Setter TargetName="ContentSite" Property="Width" Value="30" />
                                        <Setter TargetName="Border" Property="Background" Value="#FFD4D0C8" />
                                    <Trigger Property="IsEnabled" Value="False">
                                        <Setter TargetName="Border" Property="Background" Value="#FF6E6C67" />
                                    <Trigger Property="IsMouseOver" Value="true">
                                        <Setter Property="FontWeight" Value="Bold" />
                    <Setter Property="HeaderTemplate">
                                <ContentPresenter Content="{TemplateBinding Content}">
                                        <RotateTransform Angle="270" />
                    <Setter Property="Background" Value="#FF6E6C67" />
                    <Setter Property="Height" Value="90" />
                    <Setter Property="Margin" Value="0" />
                    <Setter Property="Padding" Value="0" />
                    <Setter Property="FontFamily" Value="DokChampa" />
                    <Setter Property="FontSize" Value="16" />
                    <Setter Property="VerticalAlignment" Value="Top" />
                    <Setter Property="HorizontalAlignment" Value="Right" />
                    <Setter Property="UseLayoutRounding" Value="False" />
                <Style x:Key="tabGrids">
                    <Setter Property="Grid.Background" Value="#FFE5E5E5" />
                    <Setter Property="Grid.Margin" Value="6,10,10,10" />
            <TabItem Header="Planner">
                <Grid Style="{StaticResource tabGrids}"/>
            <TabItem Header="Section 2">
                <Grid Style="{StaticResource tabGrids}"/>
            <TabItem Header="Section III">
                <Grid Style="{StaticResource tabGrids}"/>
            <TabItem Header="Section 04">
                <Grid Style="{StaticResource tabGrids}"/>
            <TabItem Header="Tools">
                <Grid Style="{StaticResource tabGrids}"/>


enter image description here

'cannot open git-upload-pack' error in Eclipse when cloning or pushing git repository

In my case, it turned out that global proxy settings in "Preferences->Network connections" were interfering with git. Which is kind of confusing, because git has dedicated property for proxy configuration. Anyway, I've added repository host to "Proxy bypass" list and the problem was gone.

Getting path relative to the current working directory?

You can use Environment.CurrentDirectory to get the current directory, and FileSystemInfo.FullPath to get the full path to any location. So, fully qualify both the current directory and the file in question, and then check whether the full file name starts with the directory name - if it does, just take the appropriate substring based on the directory name's length.

Here's some sample code:

using System;
using System.IO;

class Program
    public static void Main(string[] args)
        string currentDir = Environment.CurrentDirectory;
        DirectoryInfo directory = new DirectoryInfo(currentDir);
        FileInfo file = new FileInfo(args[0]);

        string fullDirectory = directory.FullName;
        string fullFile = file.FullName;

        if (!fullFile.StartsWith(fullDirectory))
            Console.WriteLine("Unable to make relative path");
            // The +1 is to avoid the directory separator
            Console.WriteLine("Relative path: {0}",

I'm not saying it's the most robust thing in the world (symlinks could probably confuse it) but it's probably okay if this is just a tool you'll be using occasionally.

Returning boolean if set is empty

If you want to return True for an empty set, then I think it would be clearer to do:

return c == set()

i.e. "c is equal to an empty set".

(Or, for the other way around, return c != set()).

In my opinion, this is more explicit (though less idiomatic) than relying on Python's interpretation of an empty set as False in a boolean context.

AppStore - App status is ready for sale, but not in app store

You may also need to provide your contact info, bank info, and tax info in this page so it will allow your last release on App Store:

Problems with local variable scope. How to solve it?

not Error:

JSONObject json1 = getJsonX();


JSONObject json2 = null;
if(x == y)
   json2 = getJSONX();

Error: Local variable statement defined in an enclosing scope must be final or effectively final.

But you can write:

JSONObject json2 = (x == y) ? json2 = getJSONX() : null;

Android 5.0 - Add header/footer to a RecyclerView

I haven't tried this, but I would simply add 1 (or 2, if you want both a header and footer) to the integer returned by getItemCount in your adapter. You can then override getItemViewType in your adapter to return a different integer when i==0:

createViewHolder is then passed the integer you returned from getItemViewType, allowing you to create or configure the view holder differently for the header view:, int)

Don't forget to subtract one from the position integer passed to bindViewHolder.

What exactly are iterator, iterable, and iteration?

iterable = [1, 2] 

iterator = iter(iterable)




  1. iterable is an object that can be looped over. e.g. list , string , tuple etc.

  2. using the iter function on our iterable object will return an iterator object.

  3. now this iterator object has method named __next__ (in Python 3, or just next in Python 2) by which you can access each element of iterable.




"The specified Android SDK Build Tools version (26.0.0) is ignored..."

just clean and make project / rebuilt fixed my issue give a try :-)

How to declare a static const char* in your header file?

With C++11 you can use the constexpr keyword and write in your header:

    static constexpr const char* SOMETHING = "something";


  • constexpr makes SOMETHING a constant pointer so you cannot write

    SOMETHING = "something different";

    later on.

  • Depending on your compiler, you might also need to write an explicit definition in the .cpp file:

    constexpr const char* MyClass::SOMETHING;

Split String by delimiter position using oracle SQL

Therefore, I would like to separate the string by the furthest delimiter.

I know this is an old question, but this is a simple requirement for which SUBSTR and INSTR would suffice. REGEXP are still slower and CPU intensive operations than the old subtsr and instr functions.

  2    ( SELECT 'F/P/O' str FROM dual
  3    )
  4  SELECT SUBSTR(str, 1, Instr(str, '/', -1, 1) -1) part1,
  5         SUBSTR(str, Instr(str, '/', -1, 1) +1) part2
  7  /

----- -----
F/P   O

As you said you want the furthest delimiter, it would mean the first delimiter from the reverse.

You approach was fine, but you were missing the start_position in INSTR. If the start_position is negative, the INSTR function counts back start_position number of characters from the end of string and then searches towards the beginning of string.

How do I update the password for Git?

In my Windows machine, I tried the solution of @nzrytmn i.e., Control Panel>Search Credentials>Select "ManageCredentials">modified new credentials under git option category corresponding to my username. And then,

Deleted current password:

git config --global --unset user.password

Added new password:

git config --global --add user.password "new_password"

And It worked for me.

How to set-up a favicon?

Try put this in the head of the document: <link rel="shortcut icon" type="image/x-icon" href="/favicon.ico"/>

How to make an Asynchronous Method return a value?

From C# 5.0, you can specify the method as

public async Task<bool> doAsyncOperation()
    // do work
    return true;

bool result = await doAsyncOperation();

How do you plot bar charts in gnuplot?

Simple bar graph:

bar graph

set boxwidth 0.5
set style fill solid
plot "data.dat" using 1:3:xtic(2) with boxes


0 label       100
1 label2      450
2 "bar label" 75

If you want to style your bars differently, you can do something like:

multi color bar graph

set style line 1 lc rgb "red"
set style line 2 lc rgb "blue"

set style fill solid
set boxwidth 0.5

plot "data.dat" every ::0::0 using 1:3:xtic(2) with boxes ls 1, \
     "data.dat" every ::1::2 using 1:3:xtic(2) with boxes ls 2

If you want to do multiple bars for each entry:


0     5
0.5   6

1.5   3
2     7

3     8
3.5   1


set xtics ("label" 0.25, "label2" 1.75, "bar label" 3.25,)

set boxwidth 0.5
set style fill solid

plot 'data.dat' every 2    using 1:2 with boxes ls 1,\
     'data.dat' every 2::1 using 1:2 with boxes ls 2


If you want to be tricky and use some neat gnuplot tricks:

Gnuplot has psuedo-columns that can be used as the index to color:

plot 'data.dat' using 1:2:0 with boxes lc variable


Further you can use a function to pick the colors you want:

mycolor(x) = ((x*11244898) + 2851770)
plot 'data.dat' using 1:2:(mycolor($0)) with boxes lc rgb variable


Note: you will have to add a couple other basic commands to get the same effect as the sample images.

Could not find a version that satisfies the requirement <package>

Same error in slightly different circumstances, on MacOs. Apparently setuptools versions past 45 can expose some issues and this command got me past it: pip3 install setuptools==45

Get content of a cell given the row and column numbers

Try =index(ARRAY, ROW, COLUMN)

where: Array: select the whole sheet Row, Column: Your row and column references

That should be easier to understand to those looking at the formula.

Change hover color on a button with Bootstrap customization

I had to add !important to get it to work. I also made my own class button-primary-override.

    background-color: #42A5F5 !important;
    border-color: #42A5F5 !important;
    background-image: none !important;
    border: 0 !important;

How can I enable "URL Rewrite" Module in IIS 8.5 in Server 2012?

Worth mentioning: you should download the x64 version!

From the main download page ( click "additional downloads" (under the main download button) and download the x64 version (because for some reason - the default download version is x86)

How can I merge two MySQL tables?

You can also try:

  INTO table_1 
  FROM table_2

which allows those rows in table_1 to supersede those in table_2 that have a matching primary key, while still inserting rows with new primary keys.


   INTO table_1
   FROM table_2

will update those rows already in table_1 with the corresponding row from table_2, while inserting rows with new primary keys.

How to select an option from drop down using Selenium WebDriver C#?

Selenium WebDriver C# code for selecting item from Drop Down:

IWebElement EducationDropDownElement = driver.FindElement(By.Name("education"));
SelectElement SelectAnEducation = new SelectElement(EducationDropDownElement);

There are 3 ways to select drop down item: i)Select by Text ii) Select by Index iii) Select by Value

Select by Text:

SelectAnEducation.SelectByText("College");//There are 3 items - Jr.High, HighSchool, College

Select by Index:

SelectAnEducation.SelectByIndex(2);//Index starts from 0. so, 0 = Jr.High 1 = HighSchool 2 = College

Select by Value:

SelectAnEducation.SelectByValue("College");//There are 3 values - Jr.High, HighSchool, College

Left Outer Join using + sign in Oracle 11g

TableA LEFT OUTER JOIN TableB is equivalent to TableB RIGHT OUTER JOIN Table A.

In Oracle, (+) denotes the "optional" table in the JOIN. So in your first query, it's a P LEFT OUTER JOIN S. In your second query, it's S RIGHT OUTER JOIN P. They're functionally equivalent.

In the terminology, RIGHT or LEFT specify which side of the join always has a record, and the other side might be null. So in a P LEFT OUTER JOIN S, P will always have a record because it's on the LEFT, but S could be null.

See this example from for additional explanation.

To clarify, I guess I'm saying that terminology doesn't matter, as it's only there to help visualize. What matters is that you understand the concept of how it works.


I've seen some confusion about what matters in determining RIGHT vs LEFT in implicit join syntax.


WHERE A.column = B.column(+)


WHERE B.column(+) = A.column

All I did is swap sides of the terms in the WHERE clause, but they're still functionally equivalent. (See higher up in my answer for more info about that.) The placement of the (+) determines RIGHT or LEFT. (Specifically, if the (+) is on the right, it's a LEFT JOIN. If (+) is on the left, it's a RIGHT JOIN.)

Types of JOIN

The two styles of JOIN are implicit JOINs and explicit JOINs. They are different styles of writing JOINs, but they are functionally equivalent.

See this SO question.

Implicit JOINs simply list all tables together. The join conditions are specified in a WHERE clause.

Implicit JOIN

WHERE A.column = B.column(+)

Explicit JOINs associate join conditions with a specific table's inclusion instead of in a WHERE clause.

Explicit JOIN

LEFT OUTER JOIN B ON A.column = B.column

These Implicit JOINs can be more difficult to read and comprehend, and they also have a few limitations since the join conditions are mixed in other WHERE conditions. As such, implicit JOINs are generally recommended against in favor of explicit syntax.

What is the (function() { } )() construct in JavaScript?

That is saying execute immediately.

so if I do:

var val = (function(){
     var a = 0;  // in the scope of this function
     return function(x){
         a += x;
         return a;

alert(val(10)); //10
alert(val(11)); //21


Second Example:

var val = (function(){
     return 13 + 5;

alert(val); //18

SQL Server procedure declare a list

You can convert the list of passed values into a table valued parameter and then select against this list

SET @list = '1,2,5,7,10';

DECLARE @nextpos INT
DECLARE @valuelen INT
DECLARE @tbl TABLE (number int NOT NULL)

SELECT @pos = 0, @nextpos = 1;

WHILE @nextpos > 0
    SELECT @nextpos = charindex(',', @list, @pos + 1)
    SELECT @valuelen = CASE WHEN @nextpos > 0
                            THEN @nextpos
                            ELSE len(@list) + 1
                        END - @pos - 1
    INSERT @tbl (number)
        VALUES (convert(int, substring(@list, @pos + 1, @valuelen)))
    SELECT @pos = @nextpos;

SELECT * FROM DBTable WHERE id IN (SELECT number FROM @tbl);

In this example the string passed in '1,2,5,7,10' is split by the commas and each value is added as a new row within the @tbl table variable. This can then be selected against using standard SQL.

If you intend to reuse this functionality you could go further and convert this into a function.

How to convert flat raw disk image to vmdk for virtualbox or vmplayer?

Since the question mentions VirtualBox, this one works currently:

VBoxManage convertfromraw imagefile.dd vmdkname.vmdk --format VMDK

Run it without arguments for a few interesting details (notably the --variant flag):

VBoxManage convertfromraw

Choose File Dialog

Was looking for a file/folder browser myself recently and decided to make a new explorer activity (Android library):

Matching Test application is a sample how to use.

Allows picking directories and files from phone file structure.

How to export data with Oracle SQL Developer?

To export data you need to right click on your results and select export data, after which you will be asked for a specific file format such as insert, loader, or text etc. After selecting this browse your directory and select the export destination.

How to pass a value to razor variable from javascript variable?

here is my solution that works:

in my form i use:

@using (Html.BeginForm("RegisterOrder", "Account", FormMethod.Post, new { @class = "form", role = "form" }))

   @Html.TextBoxFor(m => m.Email, new { @class = "form-control" })

   @Html.HiddenFor(m => m.quantity, new { id = "quantity", Value = 0 })


in my file.js I get the quantity from a GET request and pass the variable as follows to the form:

        method: 'Get',
        url: "" + usr
        .success(function (data){


            function setQuantity(number) {


Python MySQLdb TypeError: not all arguments converted during string formatting

I encountered this error while executing SELECT * FROM table; I traced the error to line 195.

if args is not None:
        if isinstance(args, dict):
            nargs = {}
            for key, item in args.items():
                if isinstance(key, unicode):
                    key = key.encode(db.encoding)
                nargs[key] = db.literal(item)
            args = nargs
            args = tuple(map(db.literal, args))
            query = query % args
        except TypeError as m:
            raise ProgrammingError(str(m))

Given that I am entering any extra parameters, I got rid of all of "if args ..." branch. Now it works.

using facebook sdk in Android studio


For Android Studio 0.5.5 and later, and with later versions of the Facebook SDK, this process is much simpler than what is documented below (which was written for earlier versions of both). If you're running the latest, all you need to do is this:

  1. Download the Facebook SDK from
  2. Unzip the archive
  3. In Android Studio 0.5.5 or later, choose "Import Module" from the File menu.
  4. In the wizard, set the source path of the module to import as the "facebook" directory inside the unpacked archive. (Note: If you choose the entire parent folder, it will bring in not only the library itself, but also all of the sample apps, each as a separate module. This may work but probably isn't what you want).
  5. Open project structure by Ctrl + Shift + Alt + S and then select dependencies tab. Click on + button and select Module Dependency. In the new window pop up select :facebook.
  6. You should be good to go.

Instructions for older Android Studio and older Facebook SDK

This applies to Android Studio 0.5.4 and earlier, and makes the most sense for versions of the Facebook SDK before Facebook offered Gradle build files for the distribution. I don't know in which version of the SDK they made that change.

Facebook's instructions under "Import the SDK into an Android Studio Project" on their page are wrong for Gradle-based projects (i.e. your project was built using Android Studio's New Project wizard and/or has a build.gradle file for your application module). Follow these instructions instead:

  1. Create a libraries folder underneath your project's main directory. For example, if your project is HelloWorldProject, you would create a HelloWorldProject/libraries folder.

  2. Now copy the entire facebook directory from the SDK installation into the libraries folder you just created.

  3. Delete the libs folder in the facebook directory. If you like, delete the, build.xml, .classpath, and .project. files as well. You don't need them.

  4. Create a build.gradle file in the facebook directory with the following contents:

    buildscript {
        repositories {
        dependencies {
            classpath ''
    apply plugin: 'android-library'
    dependencies {
        compile ''
    android {
        compileSdkVersion 17
        buildToolsVersion "19.0.0"
        defaultConfig {
            minSdkVersion 7
            targetSdkVersion 16
        sourceSets {
            main {
                manifest.srcFile 'AndroidManifest.xml'
                java.srcDirs = ['src']
                resources.srcDirs = ['src']
                res.srcDirs = ['res']

    Note that depending on when you're following these instructions compared to when this is written, you may need to adjust the classpath '' line to reference a newer version of the Gradle plugin. Soon we will require version 0.7 or later. Try it out, and if you get an error that a newer version of the Gradle plugin is required, that's the line you have to edit.

  5. Make sure the Android Support Library in your SDK manager is installed.

  6. Edit your settings.gradle file in your application’s main directory and add this line:

    include ':libraries:facebook'
  7. If your project is already open in Android Studio, click the "Sync Project with Gradle Files" button in the toolbar. Once it's done, the facebook module should appear. enter image description here

  8. Open the Project Structure dialog. Choose Modules from the left-hand list, click on your application’s module, click on the Dependencies tab, and click on the + button to add a new dependency. enter image description here
  9. Choose “Module dependency”. It will bring up a dialog with a list of modules to choose from; select “:libraries:facebook”. enter image description here
  10. Click OK on all the dialogs. Android Studio will automatically resynchronize your project (making it unnecessary to click that "Sync Project with Gradle Files" button again) and pick up the new dependency. You should be good to go.

How to place a div below another div?

You have set #slider as absolute, which means that it "is positioned relative to the nearest positioned ancestor" (confusing, right?). Meanwhile, #content div is placed relative, which means "relative to its normal position". So the position of the 2 divs is not related.

You can read about CSS positioning here

If you set both to relative, the divs will be one after the other, as shown here:

#slider {

#slider img {

#content {

#content #text {

Adding and removing extensionattribute to AD object

I used the following today - It works!

Add a value to an extensionAttribute

 $ThisUser = Get-ADUser -Identity $User -Properties extensionAttribute1
    Set-ADUser –Identity $ThisUser -add @{"extensionattribute1"="MyString"}

Remove a value from an extensionAttribute

  $ThisUser = Get-ADUser -Identity $User -Properties extensionAttribute1
  Set-ADUser –Identity $ThisUser -Clear "extensionattribute1" 

Validate email with a regex in jQuery

Email: {
                      group: '.col-sm-3',
                      enabled: false,
                      validators: {
                          //emailAddress: {
                          //    message: 'Email not Valid'
                          regexp: {
                              regexp: '^[^@\\s]+@([^@\\s]+\\.)+[^@\\s]+$',
                              message: 'Email not Valid'

How to create a directive with a dynamic template in AngularJS?

If you want to use AngularJs Directive with dynamic template, you can use those answers,But here is more professional and legal syntax of it.You can use templateUrl not only with single value.You can use it as a function,which returns a value as url.That function has some arguments,which you can use.

Using Javascript can you get the value from a session attribute set by servlet in the HTML page

    $sessionDetails = $this->Session->read('Auth.User');

    if (!empty($sessionDetails)) {

        $loginFlag = 1;
        # code...
        $loginFlag =  0;


<script type="text/javascript">

    var sessionValue = '<?php echo $loginFlag; ?>';
    if (sessionValue = 0) {

        //model show

How can I remove text within parentheses with a regex?

If a path may contain parentheses then the r'\(.*?\)' regex is not enough:

import os, re

def remove_parenthesized_chunks(path, safeext=True, safedir=True):
    dirpath, basename = os.path.split(path) if safedir else ('', path)
    name, ext = os.path.splitext(basename) if safeext else (basename, '')
    name = re.sub(r'\(.*?\)', '', name)
    return os.path.join(dirpath, name+ext)

By default the function preserves parenthesized chunks in directory and extention parts of the path.


>>> f = remove_parenthesized_chunks
>>> f("Example_file_(extra_descriptor).ext")
>>> path = r"c:\dir_(important)\example(extra).ext(untouchable)"
>>> f(path)
>>> f(path, safeext=False)
>>> f(path, safedir=False)
>>> f(path, False, False)
>>> f(r"c:\(extra)\example(extra).ext", safedir=False)

JQuery post JSON object to a server

To send json to the server, you first have to create json

function sendData() {
        url: '/helloworld',
        type: 'POST',
        contentType: 'application/json',
        data: JSON.stringify({
        dataType: 'json'

This is how you would structure the ajax request to send the json as a post var.

function sendData() {
        url: '/helloworld',
        type: 'POST',
        data: { json: JSON.stringify({
        dataType: 'json'

The json will now be in the json post var.

Make column fixed position in bootstrap

Use this, works for me and solve problems with small screen.

<div class="row">
    <!-- (fixed content) JUST VISIBLE IN LG SCREEN -->
    <div class="col-lg-3 device-lg visible-lg">
       <div class="affix">
           fixed position 
    <div class="col-lg-9">
    <!-- (fixed content) JUST VISIBLE IN NO LG SCREEN -->
    <div class="device-sm visible-sm device-xs visible-xs device-md visible-md ">
           NO fixed position
       Normal data enter code here

How to list physical disks?


wmic is a very complete tool

wmic diskdrive list

provide a (too much) detailed list, for instance

for less info

wmic diskdrive list brief 


Sebastian Godelet mentions in the comments:

In C:

system("wmic diskdrive list");

As commented, you can also call the WinAPI, but... as shown in "How to obtain data from WMI using a C Application?", this is quite complex (and generally done with C++, not C).


Or with PowerShell:

Get-WmiObject Win32_DiskDrive

Is there a workaround for ORA-01795: maximum number of expressions in a list is 1000 error?

I ran into this issue recently and figured out a cheeky way of doing it without stringing together additional IN clauses

You could make use of Tuples

SELECT field1, field2, field3
FROM table1
WHERE (1, name) IN ((1, value1), (1, value2), (1, value3),.....(1, value5000));

Oracle does allow >1000 Tuples but not simple values. More on this here,

This is of course if you don't have the option of using a subquery inside IN to get the values you need from a temp table.

What is deserialize and serialize in JSON?

JSON is a format that encodes objects in a string. Serialization means to convert an object into that string, and deserialization is its inverse operation (convert string -> object).

When transmitting data or storing them in a file, the data are required to be byte strings, but complex objects are seldom in this format. Serialization can convert these complex objects into byte strings for such use. After the byte strings are transmitted, the receiver will have to recover the original object from the byte string. This is known as deserialization.

Say, you have an object:

{foo: [1, 4, 7, 10], bar: "baz"}

serializing into JSON will convert it into a string:


which can be stored or sent through wire to anywhere. The receiver can then deserialize this string to get back the original object. {foo: [1, 4, 7, 10], bar: "baz"}.

What is the difference between a framework and a library?

I think you pinned down quite well the difference: the framework provides a frame in which we do our work... Somehow, it is more "constraining" than a simple library.
The framework is also supposed to add consistency to a set of libraries.

How to import jquery using ES6 syntax?

If you are not using any JS build tools/NPM, then you can directly include Jquery as:

import  '';
const $ = window.$;

You may skip import(Line 1) if you already included jquery using script tag under head.

Can VS Code run on Android?

There is a browser-based implementation of VSC that allows you to run it on a browser on your Android (or any other) device. Check it out here:

How to "pull" from a local branch into another one?

Quite old post, but it might help somebody new into git.

I will go with

git rebase master
  • much cleaner log history and no merge commits (if done properly)
  • need to deal with conflicts, but it's not that difficult.

LINQ: Select an object and change some properties without creating a new object

There shouldn't be any LINQ magic keeping you from doing this. Don't use projection though that'll return an anonymous type.

User u = UserCollection.FirstOrDefault(u => u.Id == 1);
u.FirstName = "Bob"

That will modify the real object, as well as:

foreach (User u in UserCollection.Where(u => u.Id > 10)
    u.Property = SomeValue;

change figure size and figure format in matplotlib

The first part (setting the output size explictly) isn't too hard:

import matplotlib.pyplot as plt
list1 = [3,4,5,6,9,12]
list2 = [8,12,14,15,17,20]
fig = plt.figure(figsize=(4,3))
ax = fig.add_subplot(111)
ax.plot(list1, list2)
fig.savefig('fig1.png', dpi = 300)

But after a quick google search on matplotlib + tiff, I'm not convinced that matplotlib can make tiff plots. There is some mention of the GDK backend being able to do it.

One option would be to convert the output with a tool like imagemagick's convert.

(Another option is to wait around here until a real matplotlib expert shows up and proves me wrong ;-)

Clear text input on click with AngularJS

Inspired from Robert's answer, but when we use,

ng-click="searchAll = null" in the filter, it makes the model values as null and in-turn the search doesn't work with its normal functionality, so it would be better enough to use ng-click="searchAll = ''" instead

Using Tkinter in python to edit the title bar

Here it is nice and simple.

root = tkinter.Tk()
root.title('My Title')

root is the window you create and root.title() sets the title of that window.

how to set auto increment column with sql developer

How to do it with Oracle SQL Developer: In the Left pane, under the connections you will find "Sequences", right click and select create a new sequence from the context sensitive pop up. Fill out the details: Schema name, sequence_name, properties(start with value, min value, max value, increment value etc.) and click ok. Assuming that you have a table with a key that uses this auto_increment, while inserting in this table just give "your_sequence_name.nextval" in the field that utilizes this property. I guess this should help! :)

Python error when trying to access list by index - "List indices must be integers, not str"

player['score'] is your problem. player is apparently a list which means that there is no 'score' element. Instead you would do something like:

name, score = player[0], player[1]
return name + ' ' + str(score)

Of course, you would have to know the list indices (those are the 0 and 1 in my example).

Something like player['score'] is allowed in python, but player would have to be a dict.

You can read more about both lists and dicts in the python documentation.

"cannot be used as a function error"

You are using growthRate both as a variable name and a function name. The variable hides the function, and then you are trying to use the variable as if it was the function - that is not valid.

Rename the local variable.

List file using ls command in Linux with full path

There is more than one way to do that, the easiest I think would be:

find /mnt/mediashare/net/

also this should work:

(cd /mnt/mediashare/net/; ls | xargs -i echo `pwd`/{})

How to find whether a number belongs to a particular range in Python?

I would use the numpy library, which would allow you to do this for a list of numbers as well:

from numpy import array
a = array([1, 2, 3, 4, 5, 6,])
a[a < 2]

For Loop on Lua

Your problem is simple:

names = {'John', 'Joe', 'Steve'}
for names = 1, 3 do
  print (names)

This code first declares a global variable called names. Then, you start a for loop. The for loop declares a local variable that just happens to be called names too; the fact that a variable had previously been defined with names is entirely irrelevant. Any use of names inside the for loop will refer to the local one, not the global one.

The for loop says that the inner part of the loop will be called with names = 1, then names = 2, and finally names = 3. The for loop declares a counter that counts from the first number to the last, and it will call the inner code once for each value it counts.

What you actually wanted was something like this:

names = {'John', 'Joe', 'Steve'}
for nameCount = 1, 3 do
  print (names[nameCount])

The [] syntax is how you access the members of a Lua table. Lua tables map "keys" to "values". Your array automatically creates keys of integer type, which increase. So the key associated with "Joe" in the table is 2 (Lua indices always start at 1).

Therefore, you need a for loop that counts from 1 to 3, which you get. You use the count variable to access the element from the table.

However, this has a flaw. What happens if you remove one of the elements from the list?

names = {'John', 'Joe'}
for nameCount = 1, 3 do
  print (names[nameCount])

Now, we get John Joe nil, because attempting to access values from a table that don't exist results in nil. To prevent this, we need to count from 1 to the length of the table:

names = {'John', 'Joe'}
for nameCount = 1, #names do
  print (names[nameCount])

The # is the length operator. It works on tables and strings, returning the length of either. Now, no matter how large or small names gets, this will always work.

However, there is a more convenient way to iterate through an array of items:

names = {'John', 'Joe', 'Steve'}
for i, name in ipairs(names) do
  print (name)

ipairs is a Lua standard function that iterates over a list. This style of for loop, the iterator for loop, uses this kind of iterator function. The i value is the index of the entry in the array. The name value is the value at that index. So it basically does a lot of grunt work for you.

crop text too long inside div

   .cut_text {_x000D_
      white-space: nowrap; _x000D_
      width: 200px; _x000D_
      border: 1px solid #000000;_x000D_
      overflow: hidden;_x000D_
      text-overflow: ellipsis;_x000D_
<div class="cut_text">_x000D_
very long text_x000D_

Index of Currently Selected Row in DataGridView

Try DataGridView.CurrentCellAddress.

Returns: A Point that represents the row and column indexes of the currently active cell.

E.G. Select the first column and the fifth row, and you'll get back: Point( X=1, Y=5 )

How can I position my jQuery dialog to center?

Following position parameter worked for me

position: { my: "right bottom", at: "center center", of: window },

Good luck!

get all the images from a folder in php

when you want to get all image from folder then use glob() built in function which help to get all image . But when you get all then sometime need to check that all is valid so in this case this code help you. this code will also check that it is image

  $all_files = glob("mytheme/images/myimages/*.*");
  for ($i=0; $i<count($all_files); $i++)
      $image_name = $all_files[$i];
      $supported_format = array('gif','jpg','jpeg','png');
      $ext = strtolower(pathinfo($image_name, PATHINFO_EXTENSION));
      if (in_array($ext, $supported_format))
            echo '<img src="'.$image_name .'" alt="'.$image_name.'" />'."<br /><br />";
          } else {

for more information

PHP Manual

How to put a symbol above another in LaTeX?

If you're using # as an operator, consider defining a new operator for it:


You can then write things like \pound_{n = 1}^N and get:

alt text

How to Display Selected Item in Bootstrap Button Dropdown Title

Here is my version of this which I hope can save some of your time :)

enter image description here jQuery PART:

$(".dropdown-menu").on('click', 'li a', function(){
  var selText = $(this).children("h4").html();



<div class="container">
  <div class="btn-group">
    <a class="btn btn-default dropdown-toggle btn-blog " data-toggle="dropdown" href="#" id="dropdownMenu1" style="width:200px;"><span class="selection pull-left">Select an option </span> 
      <span class="pull-right glyphiconglyphicon-chevron-down caret" style="float:right;margin-top:10px;"></span></a>

     <ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu1">
       <li><a href="#" class="" data-value=1><p> HER Can you write extra text or <b>HTLM</b></p> <h4> <span class="glyphicon glyphicon-plane"></span>  <span> Your Option 1</span> </h4></a>  </li>
       <li><a href="#" class="" data-value=2><p> HER Can you write extra text or <i>HTLM</i> or some long long long long long long long long long long text </p><h4> <span class="glyphicon glyphicon-briefcase"></span> <span>Your Option 2</span>  </h4></a>
      <li class="divider"></li>
   <li><a href="#" class="" data-value=3><p> HER Can you write extra text or <b>HTLM</b> or some </p><h4> <span class="glyphicon glyphicon-heart text-danger"></span> <span>Your Option 3</span>  </h4></a>
  <input type="text" id="vl" />

Make element fixed on scroll

Most easiest way to do it as follow:

var elementPosition = $('#navigation').offset();

        if($(window).scrollTop() >{
        } else {

Creating a PDF from a RDLC Report in the Background

The below code work fine with me of sure thanks for the above comments. You can add report viewer and change the visible=false and use the below code on submit button:

protected void Button1_Click(object sender, EventArgs e)
    Warning[] warnings;
    string[] streamIds;
    string mimeType = string.Empty;
    string encoding = string.Empty;
    string extension = string.Empty;
    string HIJRA_TODAY = "01/10/1435";
    ReportParameter[] param = new ReportParameter[3];
    param[0] = new ReportParameter("CUSTOMER_NUM", CUSTOMER_NUMTBX.Text);
    param[1] = new ReportParameter("REF_CD", REF_CDTB.Text);
    param[2] = new ReportParameter("HIJRA_TODAY", HIJRA_TODAY);

    byte[] bytes = ReportViewer1.LocalReport.Render(
        out mimeType, 
        out encoding, 
        out extension, 
        out streamIds, 
        out warnings);

    Response.Buffer = true;
    Response.ContentType = mimeType;
        "attachment; filename= filename" + "." + extension);
    Response.OutputStream.Write(bytes, 0, bytes.Length); // create the file  
    Response.Flush(); // send it to the client to download  

Get distance between two points in canvas

To find the distance between 2 points, you need to find the length of the hypotenuse in a right angle triangle with a width and height equal to the vertical and horizontal distance:

Math.hypot(endX - startX, endY - startY)

How to state in requirements.txt a direct github source

Github has a zip endpoint that in my opinion is preferable to using the git protocol. The advantages are:

  • You don't have to specify #egg=<project name>
  • Git doesn't need to be installed in your environment, which is nice for containerized environments
  • It works much better with pip hashing
  • The URL structure is easier to remember and more discoverable

You usually want requirements.txt entries to look like this, e.g. without the -e prefix:

To install from main branch:

Removing input background colour for Chrome autocomplete?

The solution of Daniel Fairweather (Removing input background colour for Chrome autocomplete?) (I would love to upvote his solution, but still need 15 rep) works really good. There is a really huge difference with most upvoted solution : you can keep background images ! But a little modification (just Chrome check)

And you need to keep in mind, it ONLY works on visible fields !

So you if you are using $.show() for your form, you need to run this code After show() event

My full solution (I have a show/hide buttons for login form ):

 if (!self.isLoginVisible()) {
        var container = $("#loginpage");
        if (navigator.userAgent.toLowerCase().indexOf("chrome") >= 0) {

            var documentForms = document.forms;
            for (i = 0; i < documentForms.length; i++) {
                for (j = 0; j < documentForms[i].elements.length; j++) {
                    var input = documentForms[i].elements[j];

                    if (input.type == "text" || input.type == "password" || input.type == null) {
                        var text = input.value;
                        var event = document.createEvent('TextEvent');
                        event.initTextEvent('textInput', true, true, window, 'a');
                        input.value = text;

    } else {

Sorry again, I would prefer it to be a comment.

If you want, I can put a link to the site where I used it.

Getting "Could not find function xmlCheckVersion in library libxml2. Is libxml2 installed?" when installing lxml through pip

set STATICBUILD=true && pip install lxml

run this command instead, must have VS C++ compiler installed first

It works for me with Python 3.5.2 and Windows 7

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  1. make a folder and open git bash from there

  2. in the git bash,

    git clone [email protected]:Example/projectName.git

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compile ''

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